Tag: Cell Biology

Categories
News

* How norovirus gets inside cells: New clues

Norovirus is the most common viral cause of diarrhea worldwide, but scientists still know little about how it infects people and causes disease because the virus grows poorly in the lab. The discovery, in mice, provides new ways to study a virus notoriously hard to work with and may lead to treatments or a vaccine.

Researchers at Washington University School of Medicine in St. Louis have identified the protein that norovirus — shown here in a colored transmission electron micrograph — uses to invade cells. Norovirus is the most common viral cause of diarrhea worldwide, but scientists still know little about how it infects people and causes disease because the virus grows poorly in the lab. The discovery, in mice, provides new ways to study a virus notoriously hard to work with and may lead to treatments or a vaccine.

Now, researchers at Washington University School of Medicine in St. Louis have identified the protein that norovirus uses to invade cells. The discovery, in mice, provides new ways to study a virus notoriously hard to work with and may lead to treatments or a vaccine.

“Our inability to grow the virus in the lab has limited our ability to develop anti-viral agents. If you can’t get the virus to multiply in human cells, how are you going to find compounds that inhibit multiplication?” said Herbert “Skip” Virgin, MD, PhD, the Mallinckrodt Professor and Chair of the Department of Pathology and Immunology and the study’s senior author. “This discovery provides a good basis for our mouse model, which we can then use to understand noroviral pathogenesis and search for treatments in people.” The research is published August 18 in Science.

Norovirus is infamous for causing outbreaks of diarrhea, vomiting and stomach cramps on cruise ships, in military barracks and in other environments where people live in close quarters. For most people, infection leads to an uncomfortable day or two punctuated with frequent trips to the bathroom, but in vulnerable populations such as cancer patients and older people, the disease can be long-lasting and sometimes deadly.

There are many noroviruses, but each is restricted to infecting just one animal species. Human norovirus will not infect any of the species typically used in biomedical research, such as mice, rats or rabbits. Human norovirus won’t grow even in human cells in petri dishes.

“Since human norovirus won’t grow in human cell lines or laboratory animals, you can’t test a drug, you can’t test a vaccine,” Virgin said. “You’d have to do those kinds of studies in people, but it would be better if we can first conduct tests in animal models.”

When mouse norovirus was discovered in 2003, it seemed like a great opportunity to make a mouse model of norovirus infection. The genomes of mouse and human norovirus are very similar, and the viruses even look alike under the electron microscope. Nobody could ever be sure, however, that how mouse norovirus acts in mice is relevant to how human norovirus acts in humans.

Virgin and postdoctoral researchers Craig Wilen, MD, PhD, and Robert Orchard, PhD, thought that if they could identify the reason that mouse norovirus infects only mice and human norovirus infects only humans, they could improve their model of norovirus infection.

The researchers used a genetic tool known as CRISPR-Cas9 to identify mouse genes that are important for mouse noroviral infection. They found that when a gene called CD300lf was knocked down by CRISPR-Cas9, norovirus could not infect the cells. CD300lf codes for a protein on the surface of mouse cells, and the researchers believe the virus latches on to it to get inside the cell.

Furthermore, when the researchers expressed mouse CD300lf protein on the surface of human cells, mouse norovirus was able to infect the human cells and multiply. “Mouse norovirus grew just fine in human cells,” Virgin said. “This tells us that the species restriction is due to the ability to get inside the cells in the first place. Once inside the cells, most likely all the other mechanisms are conserved between human and mouse noroviruses, since the viruses are so similar.”

The researchers also found that mouse norovirus requires a second molecule, or cofactor, to infect cells; CD300lf by itself isn’t enough. But they were unable to nail down the molecule’s identity.

“At this point we know more about what it isn’t than what it is,” said Orchard, a co-lead author on the study. “Every week there’s a new favorite hypothesis. It’s probably a small molecule found in the blood, not a protein.”

It is unusual for a virus to require a cofactor for infection. Their discovery suggests that the lack of a necessary cofactor may be why scientists have had a difficult time growing human norovirus in the lab.

The researchers are working on ways to use human cells with the mouse CD300lf protein to study noroviral infection. One possibility is to use the system to screen drugs to block viral multiplication. Such drugs could be administered prophylactically to people around the epicenter of an outbreak, or as a treatment for immunocompromised individuals.

The discovery of the mouse receptor for norovirus also could lead to a better understanding of how the virus causes disease.

“We still don’t even know if the virus infects epithelial cells or immune cells, and that matters if you want to develop a vaccine,” said Wilen, a co-lead author on the study. “We have developed a knockout mouse that lacks CD300lf, and we are using it to identify the cell types involved. We’re hoping that a better understanding of the pathogenesis will lead to better ways to treat or prevent this very common disease.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/08/160818150000.htm Original web page at Science Daily

Categories
News

Heart muscle made from stem cells aid precision cardiovascular medicine, study shows

Heart muscle cells made from induced pluripotent stem cells faithfully mirror the expression patterns of key genes in the donor’s native heart tissue, according to researchers at the Stanford University School of Medicine. As a result, the cells can be used as a proxy to predict whether a patient is likely to experience drug-related heart damage.

The discovery validates the use of such cells to test the potential cardiotoxicity of certain drugs and to devise new therapies for conditions like cardiomyopathy. Pinpointing people who are likely to suffer heart damage before these people undergo treatment could increase the safety profile of many medications, the researchers believe.

“Thirty percent of drugs in clinical trials are eventually withdrawn due to safety concerns, which often involve adverse cardiac effects,” said Joseph Wu, MD, PhD, director of Stanford’s Cardiovascular Institute and professor of cardiovascular medicine and of radiology. “This study shows that these cells serve as a functional readout to predict how a patient’s heart might respond to particular drug treatments and identify those who should avoid certain treatments.”

Wu is the senior author of the study, which will be published online Aug. 18 in Cell Stem Cell. Cardiovascular medicine instructor Elena Matsa, PhD, is the lead author of the research.

The ability to create stem cells from easily obtained skin or blood samples has revolutionized the concept of personalized medicine and made it possible to create many types of human tissue for use in the clinic. Researchers have wondered, however, whether the process of creating stem cells, and subsequently coaxing those stem cells to become other tissues, might affect the patterns of gene expression and even the ways the specialized cells function. If so, these changes could limit their clinical usefulness.

Matsa, Wu and their colleagues created heart muscle cells, or cardiomyocytes, from iPS cells from seven people not known to have genetic predisposition to cardiac problems. They sequenced the RNA molecules made by the heart muscle cells to learn which proteins the cells were making, and how much. They then compared the results within individuals — looking at the gene expression patterns of cardiomyocytes derived from several batches of iPS cells from each person — as well as among all seven study subjects.

They also investigated how the cardiomyocytes from each person responded to increasing amounts of two drugs, one called rosiglitazone that is sometimes used to treat Type 2 diabetes and another called tacrolimus that serves as an immunosuppressant to inhibit the rejection of transplanted organs. Each of the two drugs has been associated with adverse cardiac effects in some people, but it has not been possible to predict which patients will experience heart damage.

“We found that the gene expression patterns of the iPS cell-derived cardiomyocytes from each individual patient correlated very well,” said Matsa. “But there was marked variability among the seven people, particularly in genes involved in metabolism and stress responses. In fact, one of our subjects exhibited a very abnormal expression of genes in a key metabolic pathway.”

Heart muscle cells from this person, the researchers found, responded differently than the others to exposure to rosiglitazone. Concerns about its effect on cardiac function have caused the drug to be withdrawn from the market in Europe and have strictly limited its use in the United States.

“This person’s cells produced abnormal amounts of reactive oxygen species, were unable to regenerate their mitochondria and contracted much more weakly when exposed to rosiglitazone than cells derived from the other subjects,” said Matsa.

Although the researchers were unable to identify a specific genetic mutation likely to cause such an outcome, they were able to pinpoint an important metabolic pathway involved in the response to the drug by comparing the subject’s gene expression profile with that of the others whose cells were unaffected. They were also able to correct the defect by using a genome editing technique to boost the expression of a gene in the pathway and restore normal function.

Finally, although the researchers showed that meaningful variability exists in the gene expression patterns of the seven individuals, they couldn’t yet be certain that the iPS-derived cardiomyocytes faithfully replicated each person’s native heart tissue. To investigate, they created iPS cells from another three people who had undergone either heart biopsies or transplants. They then compared the iPS-derived cardiomyocytes with the matching native heart tissue and confirmed that the gene expression patterns correlated in many significant ways — particularly for genes involved in metabolic pathways critical to cardiac function.

“Many people talk about precision medicine or precision health, but there are only few examples of how to carry it out in a clinically meaningful way,” said Wu. “I think the patient-derived iPS cell platform gives us a surrogate window into the body and allows us to not only predict the body’s function but also to learn more about key disease-associated pathways.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/08/160818131132.htm  Original web page at Science Daily

Categories
News

Hybrid treatment hunts down and kills leukemia cells

Researchers at UC Davis and Ionis Pharmaceuticals have developed a hybrid treatment that harnesses a monoclonal antibody to deliver antisense DNA to acute lymphoblastic leukemia (ALL) cells and that may lead to less toxic treatments for the disease.

The study, published in the journal Molecular Medicine, demonstrated that once delivered, the therapeutic DNA reduced levels of MXD3, a protein that helps cancer cells survive. This novel conjugate therapy showed great promise in animal models, destroying ALL cells while limiting other damage.

“We’ve shown, for the first time, that anti-CD22 antibody-antisense conjugates are a potential therapeutic agent for ALL,” said Noriko Satake, associate professor in the Department of Pediatrics at UC Davis. “This could be a new type of treatment that kills leukemia cells with few side effects.”

ALL is the most common type of childhood cancer. It is a disease in which the bone marrow makes too many immature lymphocytes, a type of white blood cell. While most children survive ALL, many patients suffer late or long-term side effects from treatment, which may include heart problems, growth and development delays, secondary cancers and infertility.

Antisense oligonucleotides are single strands of DNA that can bind to messenger RNA, preventing it from making a protein. While antisense technology has long shown therapeutic potential, getting the genetic material inside target cells has been a problem.

In the study, researchers attached antisense DNA that inhibits the MXD3 protein to an antibody that binds to CD22, a protein receptor expressed almost exclusively in ALL cells and normal B cells.

Once the antibody binds to CD22, the conjugate is drawn inside the leukemia cell, allowing the antisense molecule to prevent MXD3 production. Without this anti-apoptotic protein, ALL cells are more prone to cell death.

The hybrid treatment was effective against ALL cell lines in vitro and primary (patient-derived) ALL cells in a xenograft mouse model. Animals that received the hybrid therapy survived significantly longer than those in the control group.

Designed to be selective, the treatment only targets cells that express CD22. While it does attack healthy B cells, the therapy is expected to leave blood stem cells and other tissues unscathed.

“You really don’t want to destroy hematopoietic stem cells because then you have to do a stem cell transplant, which is an extremely intensive therapy,” noted Satake. “Our novel conjugate is designed so that it does not harm hair, eyes, heart, kidneys or other types of cells.”

While the study shows the conjugate knocked down MXD3, researchers still have to figure out how this was accomplished. In addition, they will investigate combining this treatment with other therapies. Because it hastens cell death, the conjugate could make traditional chemotherapy drugs more effective. In addition, the approach might work against other cancers.

“You can see this as proof of principle,” Satake said. “You could switch the target and substitute the antibody, which could be used to treat other cancers or even other diseases.”

Access the full report at: http://static.smallworldlabs.com/molmedcommunity/content/pdfstore/15_210_Satake.pdf

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160728155631.htm  Original web page at Science Daily

Categories
News

Shorter telomeres reveal stress in migratory birds

The stress of birds’ continent-spanning annual migrations, it appears, leads to faster aging and a potentially earlier death. A new study in The Auk: Ornithological Advances reveals that telomeres, structures on the ends of chromosomes that shorten with age, are shorter in migratory birds than in their non-migratory counterparts.

Migration lets birds take advantage of abundant food resources at high latitudes during the breeding season while escaping the region’s harsh winters. However, it’s also an enormous undertaking, and the benefits that birds gain from it come with a cost. Carolyn Bauer of North Dakota State University and her colleagues compared the telomeres — bits of non-coding DNA that shorten during cell division and stress — of migratory and resident birds from the same species, the Dark-eyed Junco. They found that the migrants had significantly shorter telomeres than birds that stayed put year-round, suggesting that the migratory birds were aging at a faster rate and that the stress of a migratory lifestyle may actually shorten birds’ lifespans.

“Whenever our cells divide, we lose a little bit of DNA on the ends of our chromosomes, and telomeres are simply non-coding regions that act as ‘protective caps,” explains Bauer. Once they reach a certain threshold of shortness, the cell dies. Importantly, exposure to stress can also make telomeres shorten faster. For their study, Bauer and her colleagues collected blood samples from 11 migratory and 21 resident juncos in Virginia, using only first-year birds to ensure that any telomere differences were not simply due to age. “I’ve been interested in measuring telomeres since I was undergraduate at the University of Washington,” says Bauer. “I remember my introductory biology professor lecturing about telomeres and how environmental stress could cause them to shorten.”

If migrating is so stressful, why keep doing it? Bauer and her colleagues believe that the costs of migration must be balanced out by the reproductive boost birds get from nesting in resource-rich northern habitats. They hope that future studies will determine whether shorter telomeres reflect the stress of migration itself or if they’re the result of decreased self-maintenance, as well as whether telomere length is negatively correlated with migratory distance.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/08/160803072812.htm Original web page at Science Daily

Categories
News

Key to regulating cell’s powerhouse discovered

Aging, neurodegenerative disorders and metabolic disease are all linked to mitochondria, structures within our cells that generate chemical energy and maintain their own DNA. In a fundamental discovery with far-reaching implications, scientists at the University of California, Davis, now show how cells control DNA synthesis in mitochondria and couple it to mitochondrial division.

The work is published July 15 in the journal Science.

“This has very profound implications for human disease,” said Jodi Nunnari, professor and chair of molecular and cellular biology at UC Davis and senior author on the paper.

Mitochondria retain their own DNA from the very distant past, when they were a type of bacteria that moved into other cells and never left. All eukaryotic cells — in plants, animals and fungi — contain mitochondria, which allow oxygen-breathing organisms to obtain energy from respiration.

In human cells, mitochondria are elongated, snaking tubes, with hundreds to thousands of copies of their single chromosome dotted around, packaged in a structure called the nucleoid. While the DNA in the cell’s nucleus comes from both parents, your mitochondrial DNA is inherited only from your mother.

While division of DNA in the cell’s nucleus is tightly controlled, synthesis and division of mitochondrial DNA is “a lot more relaxed,” Nunnari said.

How does the cell decide where all the copies of the mitochondrial DNA should go? And how is their division organized, if it is? Contact points are crucial.

Postdoctoral researcher Samantha Lewis, with undergraduate student Lauren Uchiyama, used microscopy with fluorescent dyes to tag mitochondria, their chromosomes, and the endoplasmic reticulum, a network of tubes that spreads throughout the cell.

They found that dividing mitochondrial chromosomes were located at points where the endoplasmic reticulum touches the outside of a mitochondrion. These also became the points where mitochondria divided into two offspring, a process that requires a sort of lasso of protein around the organelle that squeezes it until it splits.

“The endoplasmic reticulum comes into contact with the mitochondrion, and where they contact is where they divide,” Nunnari said.

The contact between the two organelles “licenses” the mitochondrial DNA to copy and divide, Nunnari said. This DNA division is in turn spatially coupled to division of the mitochondrion itself, and to distribution of the daughter DNA around the cell.

“There are hundreds of contact points around the cell that determine where division takes place and how mitochondria are distributed, but division preferentially occurs at the subset of contacts where mitochondrial DNA is being copied” Nunnari said. “It shows that there is a higher order to this, it is not simply random.”

The discovery has broad implications for understanding cell functions, aging and a broad range of diseases. Nunnari noted that it stemmed entirely from fundamental research.

“We didn’t come to this by studying any specific disease, it’s discovery-based research,” she said. “But this will greatly impact human health.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/07/160715113551.htm Original web page at Science Daily

Categories
News

Four steps for validating stem cells

Scientists at EPFL and in the US have developed a robust method for characterizing human embryonic stem cells and their potential for medical applications.

The key to utilizing stem cells for regenerative medicine and tissue engineering lies in a property of theirs called pluripotency. This refers to the cells’ ability to differentiate into different types of cells. This means that we need to be able to reliably obtain, culture and maintain fully pluripotent stem cells. It has been difficult to generate human embryonic stem cells at the earliest stage of pluripotency, in what is named “ground” or “naïve” state, whereas this is readily done with mouse cells. The labs of Rudolf Jaenisch at MIT, Joe Ecker at the Salk Institute, and Didier Trono at EPFL have now developed a four-step process for determining accurate signatures of human embryonic stem cells and relating them to precise developmental stages. The work, a first for human embryonic stem cells, is published in Cell Stem Cell.

The first criterion involves a rigorous assay to see how much the naïve stem cells contribute to a mouse-human embryo. If the resulting organism (a so-called “chimera”) contains any human DNA, it signals successful engraftment of the stem cells.

The second criterion looks at the expression profile of 4.5 million RNA biomarkers called “transposable elements,” which are genetic units that can move around the genome — in fact, they make up half of the human genome. Because they can cause dangerous mutations by inserting themselves inside genes, transposable elements are actually suppressed in the early developmental stages of the embryo. However, transposable elements also regulate gene expression, and are essential in maintaining the organism’s homeostasis. The researchers demonstrated that profiling which transposable elements are active in the stem cells is an extremely sensitive and highly reproducible indicator of their pluripotency stage.

The third criterion focuses on DNA methylation state of the cells, which is lower in the naïve compared to the primed state. Finally, the fourth criterion is the epigenetic state of the X chromosome in female naïve cells, which resembles that found in the human pre-implantation embryo.

The study provides a roadmap for broadly evaluating stage, state and quality of human pluripotent cells, and can overcome current limitations with using such cells in research and clinical applications. Based on this work, the researchers have developed a startup project named Cellphmed. The company’s mission is to streamline the experimental work of the second criterion, which involves the transcriptional profiling of transposable elements to generate human cell markers for broad research and clinical applications.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/07/160714135026.htm Original web page at Science Daily

Categories
News

Study shows a new role for B-complex vitamins in promoting stem cell proliferation

The study, published July 11 in Developmental Cell, shows for the first time that an adult stem cell population is controlled by an external factor arising from outside the animal–bacterial folate. In this case, that animal was a small roundworm model organism known as Caenorhabditis elegans. 

“Our study shows that germ stem cells in Caenorhabditis elegans are stimulated to divide by a specific folate that comes from their bacterial diet,” said the study’s co-senior author Edward Kipreos, a professor in UGA’s Franklin College of Arts and Sciences. “Folates are essential B-group vitamins. However, we show that the ability of a specific folate to stimulate germ cells is independent of its role as a vitamin, implying that it acts directly as a signaling molecule.”

Naturally occurring folates exist in many chemical forms; folates are found in food, as well as in metabolically active forms in the human body. Folic acid is the major synthetic form found in fortified foods and vitamin supplements.

“Since its discovery in 1945, folate has been the subject of many studies that resulted in more than 50,000 publications. The finding in this study is the first of its kind because it presents evidence that folate is involved in roles other than those that were known before,” said the study’s co-senior author Jacob Selhub, director of the Vitamin Metabolism Laboratory at Tufts University.

“Grains in the U.S. and a few other countries are currently supplemented with folates,” Kipreos said. “Folate supplementation has been an important contributor in reducing the number of neural tube birth defects. However, a vitamin-independent role of folates may provide a secondary pathway, the nature and biological impact of which for humans are yet to be determined.”

The study describes how a specific folate receptor, FOLR-1, in C. elegans is required for the stimulation of germ stem cell growth.

The research team observed a process in C. elegans in which the action of FOLR-1 is required to promote germ cell tumors that may be similar to the way folate receptors promote the progression of certain cancers in humans. With a few exceptions, folate receptors are not essential for the transport of folates into cells for use as vitamins, but may act to stimulate cell division.

As a part of the published findings, the researchers created the first system that allows C. elegans germ cells to be cultured in vitro.

“This technique provides an important new tool for the study of this major genetic model organism,” Kipreos said.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/07/160711150942.htm Original web page at Science Daily

Categories
News

Protein found to bolster growth of damaged muscle tissue

Johns Hopkins University biologists have found that a protein that plays a key role in the lives of stem cells can bolster the growth of damaged muscle tissue, a step that could potentially contribute to treatments for muscle degeneration caused by old age and diseases such as muscular dystrophy.

The results, published online by the journal Nature Medicine, show that a particular type of protein called integrin is present on the stem cell surface and used by stem cells to interact with, or “sense” their surroundings. How stem cells sense their surroundings, also known as the stem cell “niche,” affects how they live and last for regeneration. The presence of the protein β1-integrin was shown to help promote the transformation of those undifferentiated stem cells into muscle after the tissue has degraded, and improve regenerated muscle fiber growth as much as 50 percent.

While the presence of β1-integrin in adult stem cells is apparent, “its role in these cells has not been examined,” especially its influence on the biochemical signals promoting stem cell growth, wrote the three authors, Chen-Ming Fan, an adjunct biology professor; Michelle Rozo, who completed her doctorate in biology at Johns Hopkins this year; and doctoral student Liangji Li.

The experiment shows that β1-integrin — one of 28 types of integrin — maintains a link between the stem cell and its environment, and interacts biochemically with a growth factor called fibroblast growth factor [FGF] to promote stem cell growth and restoration after muscle tissue injury. Aged stem cells do not respond to FGF, and the results also show that β1-integrin restores aged stem cell’s ability to respond to FGF to grow and improve muscle regeneration.

By tracking an array of proteins inside the stem cells, the researchers tested the effects of removing β1-integrin from the stem cell. This is based on the understanding that the activities of stem cells — undifferentiated cells that can become specialized — are dependent on their environment and supported by the proteins found there.

“If we take out β1-integrin, all these other (proteins) are gone,” said Fan, the study’s senior author and a staff member at the Carnegie Institution for Science in Washington and Baltimore.

Why that is the case is not clear, but the experiment showed that without β1-integrin, stem cells could not sustain growth after muscle tissue injury.

By examining β1-integrin molecules and the array of proteins that they used to track stem cell activity in aged muscles, the authors found that all of these proteins looked like they had been removed from aged stem cells. They injected an antibody to boost β1-integrin function into aged muscles to test whether this treatment would enhance muscle regeneration. Measurements of muscle fiber growth with and without boosting the function of β1-integrin showed that the protein led to as much as 50-percent more regeneration in cases of injury in aged mice.

When the same β1-integrin function-boosting strategy was applied to mice with muscular dystrophy, the muscle was able to increase strength by about 35 percent.

Fan said the team’s research will next try to determine what is happening inside the stem cells as they react with their immediate environment, as a step to understanding more about the interaction of the two. That, in turn, could help refine the application of integrin as a therapy for muscular dystrophy and other diseases, and for age-related muscle degeneration.

“We provide here a proof-of-principle study that may be broadly applicable to muscle diseases that involve SC (stem cell) niche dysfunction,” the authors wrote. “But further refinement is needed for this method to become a viable treatment.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160719131341.htm Original web page at Science Daily

Categories
News

* Treating autoimmune disease without harming normal immunity

Preclinical study shows that engineered T cells can selectively target the antibody-producing cells that cause autoimmune disease.

In a study with potentially major implications for the future treatment of autoimmunity and related conditions, scientists from the Perelman School of Medicine at the University of Pennsylvania have found a way to remove the subset of antibody-making cells that cause an autoimmune disease, without harming the rest of the immune system. The autoimmune disease the team studied is called pemphigus vulgaris (PV), a condition in which a patient’s own immune cells attack a protein called desmoglein-3 (Dsg3) that normally adheres skin cells.

Current therapies for autoimmune disease, such as prednisone and rituximab, suppress large parts of the immune system, leaving patients vulnerable to potentially fatal opportunistic infections and cancers.

The Penn researchers demonstrated their new technique by successfully treating an otherwise fatal autoimmune disease in a mouse model, without apparent off-target effects, which could harm healthy tissue. The results are published in an online First Release paper in Science.

“This is a powerful strategy for targeting just autoimmune cells and sparing the good immune cells that protect us from infection,” said co-senior author Aimee S. Payne, MD, PhD, the Albert M. Kligman Associate Professor of Dermatology.

Payne and her co-senior author Michael C. Milone, MD, PhD, an assistant professor of Pathology and Laboratory Medicine, adapted the technique from the promising anti-cancer strategy by which T cells are engineered to destroy malignant cells in certain leukemias and lymphomas.

“Our study effectively opens up the application of this anti-cancer technology to the treatment of a much wider range of diseases, including autoimmunity and transplant rejection,” Milone said.

The key element in the new strategy is based on an artificial target-recognizing receptor, called a chimeric antigen receptor, or CAR, which can be engineered into patients’ T cells. In human trials, researchers remove some of patients’ T cells through a process similar to dialysis and then engineer them in a laboratory to add the gene for the CAR so that the new receptor is expressed in the T cells. The new cells are then multiplied in the lab before re-infusing them into the patient. The T cells use their CAR receptors to bind to molecules on target cells, and the act of binding triggers an internal signal that strongly activates the T cells — so that they swiftly destroy their targets.

The basic CAR T cell concept was first described in the late 1980s, principally as an anti-cancer strategy, but technical challenges delayed its translation into successful therapies. Since 2011, though, experimental CAR T cell treatments for B cell leukemias and lymphomas — cancers in which patients’ healthy B cells turn cancerous — have been successful in some patients for whom all standard therapies had failed.

B cells, which produce antibodies, can also cause autoimmunity. Payne researches autoimmunity, and a few years ago, a postdoctoral researcher in her laboratory, Christoph T. Ellebrecht, MD, took an interest in CAR T cell technology as a potential weapon against B cell-related autoimmune diseases. Soon Payne’s lab teamed up with Milone’s, which studies CAR T cell technology, in the hope of finding a powerful new way to treat these ailments.

“We thought we could adapt this technology that’s really good at killing all B cells in the body to target specifically the B cells that make antibodies that cause autoimmune disease,” said Milone.

“Targeting just the cells that cause autoimmunity has been the ultimate goal for therapy in this field,” noted Payne.

Ellebrecht was first author, the team took aim at pemphigus vulgaris. This condition occurs when a patient’s antibodies attack molecules that normally keep skin cells together. When left untreated, PV leads to extensive skin blistering and is almost always fatal, but in recent decades the condition has been treatable with broadly immunosuppressive drugs such as prednisone, mycophenolate mofetil, and rituximab.

To treat PV without causing broad immunosuppression, the Penn team designed an artificial CAR-type receptor that would direct patients’ T cells to attack only the B cells producing harmful anti-Dsg3 antibodies.

The team developed a “chimeric autoantibody receptor,” or CAAR, that displays fragments of the autoantigen Dsg3 — the same fragments to which PV-causing antibodies and their B cells typically bind, as Payne’s laboratory and others have shown in prior studies. The artificial receptor acts as a lure for the B cells that target Dsg3, bringing them into fatal contact with the therapeutic T cells.

Testing many variants, the team eventually found an artificial receptor design that worked well in cell culture, enabling host T cells to efficiently destroy cells producing antibodies to desmoglein, including those derived from PV patients. The engineered T cells also performed successfully in a mouse model of PV, killing desmoglein-specific B cells and preventing blistering and other manifestations of autoimmunity in the animals.

“We were able to show that the treatment killed all the Dsg3-specific B cells, a proof of concept that this approach works,” Payne said.

T cell therapies can be complicated by many factors. But in these experiments, the Penn scientists’ engineered cells maintained their potency despite the presence of anti-Dsg3 antibodies that might have swarmed their artificial receptors. In addition, there were no signs that the engineered T cells caused side effects by hitting the wrong cellular targets in the mice.

The team now plans to test their treatment in dogs, which can also develop PV and often die from the disease. “If we can use this technology to cure PV safely in dogs, it would be a breakthrough for veterinary medicine, and would hopefully pave the way for trials of this therapy in human pemphigus patients,” Payne said.

Also on the horizon for the Penn scientists are applications of CAAR T cell technology for other types of autoimmunity. The immune rejection that complicates organ transplants, and normally requires long-term immunosuppressive drug therapy, may also be treatable with CAAR T cell technology.

“If you can identify a specific marker of a B cell that you want to target, then in principle this strategy can work,” Payne said.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160630144409.htm  Original web page at Science Daily

Categories
News

Unsilencing silenced genes by CRISPR/Cas9

Scientists have developed a new technique to unleash silenced genes and change cell fates using CRISPR/Cas9.

The ability to control gene expression in cells allows scientists to understand gene function and manipulate cell fate. Recently, scientists have developed a revolutionary gene-editing tool, called CRIPSR/Cas9, which employs a system naturally used by bacteria as protection against viruses. The tool allows scientists to precisely add, remove or replace specific parts of DNA. CRISPR/Cas9 is the most efficient, inexpensive and easiest gene-editing tool available to date. However, scientists have not yet managed to effectively use it to activate genes in the cells.

A team, led by Toru Kondo at Hokkaido University’s Institute of Genetic Medicine, has developed a powerful new method that does just that.

Genes in cells have their own switches called promoters. A gene is switched off, or silenced, when its promoter is methylated. The team effectively wanted to turn on a switched-off gene.

They combined a DNA repair mechanism, called MMEJ (microhomology-mediated end-joining), with CRISPR/Cas9. They cut out a methylated promoter using CRISPR/Cas9 and then inserted an unmethylated promoter with MMEJ, replacing the off-switch with an on-switch.

The scientists used this tool on the neural cell gene OLIG2 and the embryonic stem cell gene NANOG to test its efficiency in cultured cells. Within five days, they found evidence that the genes were robustly expressed. When they turned on OLIG2 in cultured human stem cells, the cells differentiated to neurons in seven days with high efficiency.

The scientists also found that their editing tool could be used to activate other silenced promoters. In addition, they found that the system didn’t cause unwanted mutations in other non-targeted genes in the cells. The tool has wide potential to be used to manipulate gene expression, create genetic circuits, or to engineer cell fates.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160701120557.htm  Original web page at Science Daily

Categories
News

Surprising number of businesses selling unapproved stem cell ‘treatments’ in the US

At least 351 companies across the United States are marketing unapproved stem cell procedures at 570 individual clinics. Such businesses advertise “stem cell” interventions for orthopedic injuries, neurological disorders, cardiac diseases, immunological conditions, pulmonary disorders, injured spinal cords, and cosmetic indications. In Cell Stem Cell on June 30, bioethicist Leigh Turner (@LeighGTurner) and stem cell researcher Paul Knoepfler (@pknoepfler) present an analysis of U.S. businesses engaged in “direct-to-consumer” marketing of these procedures.

“In almost every state now, people can go locally to get stem cell ‘treatments,’’ says Knoepfler, of the University of California, Davis, and Shriners Hospital For Children. “Many people in larger metropolitan areas can just drive 15 minutes to find a clinic offering these kinds of services instead of, say, traveling to Mexico or the Caribbean. I think this reflects a change from what we’ve seen documented in the past and is different from what we typically think about when we think of stem cell tourism.”

Turner and Knoepfler found the businesses through Internet key word searches, text mining, and content analysis of company websites. For each business, the duo recorded the company name, location(s), website addresses, advertised stem cell types, and marketing claims concerning diseases, injuries, and conditions for which stem cells are reportedly administered. Their research should serve as a baseline for future studies of U.S. businesses engaged in direct-to-consumer advertising of purported stem cell interventions.

Key findings from the report include:

  • Clinics advertising stem cell interventions cluster in particular states. They are most likely to be found in California (113 clinics), Florida (104), Texas (71), Colorado (37), Arizona (36), and New York (21).
  • Beverly Hills is home to 18 clinics, more than any other city in the nation, followed by New York (14 clinics), San Antonio (13), Los Angeles (12), Austin (11), Scottsdale (11), and Phoenix (10).
  • Of the stem cell procedures that are marketed, 61% of businesses offer fat-derived stem cell interventions and 48% offer bone-marrow-based treatments. Advertisements for induced pluripotent stem cells (1 business), embryonic stem cells (1 business), and xenogeneic products (2 businesses) are rare.
  • Over 300 of the businesses market interventions for orthopedic issues. Other advertised conditions include pain (150 businesses), sports injuries (90), neurological diseases (80), and immune disorders (75).

“This is a marketplace that is dramatically expanding before our eyes–we were aware early on and tracked it early on, but I don’t think we knew the scope and size of the market,” says Turner, of the Center for Bioethics at the University of Minnesota. “Brakes ought to exist in a marketplace like this, but where are the brakes? Where are the regulatory bodies? And how did this entire industry come into being in a country where stem cell-based interventions and the medical devices that produce them are supposed to be regulated by the FDA?”

Turner and Knoepfler, who runs the popular stem cell blog “The Niche,” grew suspicious of an increase in American stem cell clinics when inquiries from readers and patients changed from Americans asking about going abroad for a stem cell treatment to Americans asking about seeking treatment in the United States. In investigating the people who run these clinics, Turner and Knoepfler found that not only were individuals such as cosmetic surgeons and naturopaths beginning to offer unapproved stem cell interventions, but the “pioneers” in the industry were training others to do the same. It is unclear whether federal authorities–particularly the Food & Drug Administration–and state medical boards missed the scope of the problem or are taking minimal action despite being aware of the spread of such businesses.

“From around 2009 to the present, businesses have been entering the marketplace on a routine basis, they’ve been coming in making marketing assertions about stem cells treating 30-40 different diseases, and no one’s taking meaningful regulatory action,” Turner says. “Does that mean that people are getting access to safe and efficacious interventions or is there basically unapproved human experimentation taking place where people are going to these businesses and receiving experimental investigational cell-based interventions without being given a meaningful account of the lack of knowledge and evidence that they’re being charged for?”

A separate downside is that patients who have unapproved and unproven stem cell interventions decrease their chances of qualifying for FDA-cleared and IRB-approved clinical trials that comply with federal regulations. This is a loss for stem cell research.

“Another serious consideration to think about is that over the years many people have begun to include these businesses in their overall impression of the stem cell field,” Knoepfler says. “There is a real risk that as clinics proliferate, if we don’t address it in a more proactive way, as we see negative outcomes for patients grow and people get mixed bags of information about stem cells, then this could really negatively impact the public perception of this research.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160630135852.htm Original web page at Science Daily

Categories
News

Natural metabolite can suppress inflammation

An international research team has revealed a substance produced in humans that can suppress the pro-inflammatory activity of macrophages — specific immune cells. The substance known as itaconate is released in large quantities by macrophages themselves and according to the scientists, acts as an antioxidant and anti-inflammatory agent. These properties make itaconate promising for the treatment of such pathologies as cardiac ischemia, metabolic disorders and autoimmune diseases which may be associated with excessive inflammation or oxidative stress. An international group of scientists from US, Canada, Germany and Russia has revealed a substance produced in humans that can suppress the pro-inflammatory activity of macrophages — specific cells of immune system. The substance known as itaconate is released in large quantities by macrophages themselves, but until now its role remained poorly studied. Now scientists have found evidence that itaconate acts as an antioxidant and anti-inflammatory agent. These properties make itaconate promising for the treatment of pathologies caused by excessive inflammation or oxidative stress. Such conditions may be associated with cardiac ischemia, metabolic disorders and perhaps autoimmune diseases. The findings were published in Cell Metabolism.

The work, which united scientists from Washington University in St. Louis, ITMO University, McGill University and Max Planck Institute of Immunobiology and Epigenetics, was based on the study of macrophages — immune system cells in charge of fighting pathogens. An important feature of macrophages is their ability to switch between different states depending on the concentration of various substances in the body. In total, there are three such states: M0 — neutral, M1 — pro-inflammatory and M2 anti-inflammatory.

M1 macrophages are the first who arrive to fight the infection. As they begin to swallow viruses and bacteria, an intense inflammatory process kicks in. This process may adversely affect the entire organism if the macrophages become overly diligent. Inflammation consumes energy resources of the organism and can lead to numerous complications or even death. That is why in order to mitigate the negative consequences of immune response, it is important to understand how we can reduce the excessive proinflammatory effect of macrophages.

An in-depth study of macrophage metabolism during their transition from inactive to proinflammatory state helped researchers identify the substance that could suppress macrophage-related inflammations. Describing the working mechanism of this substance called itaconate became possible due to a complex map of metabolic pathways in macrophages that was developed by the group.

Itaconate is produced by macrophages when they switch from M0 inactive state to M1 pro-inflammatory state. If the concentration of this substance increases to defined limit, macrophage activation falls. “Itaconate sets the bar controlling M1 macrophage formation,” says Alexey Sergushichev, one of the authors of the paper and PhD student at ITMO University. “Without this substance, the inflammation would increase more than required. In the future, with the help of itaconate, it will be possible to artificially manipulate the transition of macrophages from M0 to M1, meaning the possibility of restraining inflammations. The influence of itaconate on macrophages is a delicate mechanism that can ensure high selectivity of the immune system regulation.”

Prior to the study, guesswork with respect to the function and origin of itaconate generated a lot of speculations. But the new study shows that itaconate plays the role of immune regulator. To understand how itaconate reduces the activity of immune cells, the researchers examined the so-called Krebs cycle, or tricarboxylic acid cycle and cellular respiration (processes of producing of vital substances and energy from the oxidation of glucose in cells). Having done so, the scientists identified two “bottlenecks” that can be influenced to reverse the reaction and send it another way.

The Krebs cycle is preceded by signal transmission between cells through oxygen-sensitive pathways. Itaconate blocks the enzyme called Sdh (succinate dehydrogenase), which not only ensures the functioning of the tricarboxylic acid cycle but also links the cycle to cellular respiration and signaling pathways.

Thus, itaconate acts on both functions of the Sdh enzyme, adjusting the cells’ Krebs cycle and respiration. When the enzyme is blocked in macrophages, both processes become interrupted, and this impairs the cells’ activation. “Noteworthy, itaconate acts as an anti-oxidant and anti-inflammatory agent,” says Vicky Lampropoulou, the lead author of the paper and researcher at the laboratory of Maxim Artyomov at Washington University in St. Louis. “At the same time, itaconate is naturally produced by mammalian immune cells. These features make it attractive for use in adjuvant therapy for numerous diseases, in which excessive inflammation and oxidative stress associate with pathology, like heart ischemia, metabolic disorders and perhaps even autoimmunity.”

The researchers have already demonstrated that they can use itaconate to reach the desired effect in living organisms. Experiments with mice have shown that the substance reduces damage after heart attack, acting by the same mechanism of locking the Sdh enzyme. However, according to the scientists, more work is needed to successfully apply the method to humans.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/06/160630155359.htm  Original web page at Science Daily

Categories
News

The relentless dynamism of the adult brain

Scientists from the Institut Pasteur and the CNRS were able to make real-time observations over a period of several months that reveal how new adult-born neurons are formed and evolve in the olfactory bulb of mice. They made the surprising discovery that there is constant structural plasticity in the connections established by these new neurons with the circuits into which they are recruited. The scientists showed that this neuronal dynamism can enable optimal processing of sensory information by the olfactory bulb. These findings are to be published in the journal Neuron on June 30, 2016.

Although most neurons are generated during embryogenesis, some regions of the brain, such as the olfactory bulb in rodents and the hippocampus in humans, are capable of constantly regenerating their neurons in adulthood. Scientists first conclusively discovered these new adult neurons around 15 years ago, but their function remained a mystery, mainly because they are inaccessible in living animals.

In an article published in the journal Neuron, scientists from a unit at the Institut Pasteur directed by CNRS scientist Pierre-Marie Lledo provide further evidence of the highly dynamic nature of the changes observed at the neuronal level in adult brains. The scientists spent several months observing the development of neurons formed in adulthood in the olfactory bulbs of mice. This gave them the unique opportunity to see the formation, stabilization and elimination of connections between neurons in real time.

They revealed that in the olfactory bulb, where new neurons are continuously formed, the connections between these new neurons and neighboring cells are significantly rearranged throughout their lifetime. All these neurons are constantly reorganizing the billions of “synaptic” contacts they establish among themselves. The scientists were surprised by this observation. “We expected to see the synapses gradually stabilizing, as happens during brain development. But astonishingly, these synapses proved to be highly dynamic throughout the life of the new neurons. Also, these dynamics were reflected in the principal neurons, their primary synaptic partner,” explained first author, Kurt Sailor, from the Institut Pasteur.

To observe the ongoing formation of neuronal circuits, the scientists marked the new neurons with a green fluorescent protein (GFP), to allow imaging of the dynamic changes with microscopy. These experiments were carried out over a period of several months to follow the entire life cycle of the new neurons. In the first three weeks of their life, these new neurons extended their cellular projections, known as dendrites, to form several ramifications, which subsequently became very stable. They next observed the neuronal spines, the structure where synapses form, and demonstrated that 20% of the synapses between new and pre-existing neurons were changed on a daily basis — a phenomenon that was also observed in their synaptic partners, the principal olfactory bulb neurons. Using computer-based models, the authors showed that these dynamics enabled the synaptic network to adjust efficiently and reliably to ongoing sensory changes in the environment.

“Our findings suggest that the plasticity of this constantly regenerating region of the brain occurs with continuous physical formation and elimination of synaptic connections. This structural plasticity reveals a unique dynamic mechanism that is vital for the regeneration and integration of new neurons within the adult brain circuit,” concluded the scientists. More generally, this study suggests a universal plasticity mechanism in brain regions that are closely associated with memory and learning.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160701120520.htm Original web page at Science Daily

Categories
News

New anti-cancer strategy mobilizes both innate and adaptive immune response

Scientists have developed a new vaccine that involves injecting cells that have been modified so that they can stimulate both an innate immune response and the more specific adaptive response, which allows the body to keep memories and attack new tumor cells as they form.

Though a variety of immunotherapy-based strategies are being used against cancer, they are often hindered by the inability of the immune response to enter the immunosuppressive tumor microenvironment and to effectively mount a response to cancer cells. Now, scientists from the RIKEN Center for Integrative Medical Sciences have developed a new vaccine that involves injecting cells that have been modified so that they can stimulate both an innate immune response and the more specific adaptive response, which allows the body to keep memories and attack new tumor cells as they form. In the study published in Cancer Research, they found that the vaccine made it possible for killer CD8+T-cells–important players in the immune response against cancer–to enter the tumor microenvironment and target cancerous cells.

According to Shin-ichiro Fujii, leader of the Laboratory for Immunotherapy, who led the study, “Cancer cells have different sensitivities to the innate or adaptive response, so it important to target both in order to eradicate it. We have developed a special type of modified cell, called aAVC, which we found can do this.”

The aAVC cells are not taken from the subject’s own body but are foreign cells. The cells are modified by adding a natural killer t-cell ligand, which permits them to stimulate natural killer T-cells, along with an antigen associated with a cancer. The group found that when these cells are activated, they in turn promote the maturation of dendritic cells, which act as coordinators of the innate and acquired response. Dendritic cells are key because they allow the activation of immune memory, where the body remembers and responds to a threat even years later.

To find whether it worked in actual bodies, they conducted experiments in mice with a virulent form of melanoma that also expresses a model antigen called OVA. Tests in mice showed, moreover, that aggressive tumors could be shrunken by vaccinating the animals with aAVC cells that were programmed to display OVA antigen. Following the treatment, the tumors in the treated animals were smaller and necrotic in the interior–a sign that the tumor was being attacked by the killer CD8+T-cells.

Fujii continues, “We were interesting in finding a mechanism, and were able to understand that the aAVC treatment led to the development of blood vessels in the tumors that expressed a pair of important adhesion molecules, ICAM-1 and VCAM-1, that are not normally expressed in tumors. This allowed the killer CD8+T cells to penetrate into the tumor.”

They also found that in animals that had undergone the treatment, cancer cells injected even a year later were eliminated. “This indicates,” says Fujii, “that we have successfully created an immune memory that remembers the tumor and attacks it even later.”

Looking to the future, Fujii says, “Our therapy with aAVC is promising because typical immunotherapies have to be tailor-made with the patient’s own cells. In our case we use foreign cells, so they can be made with a stable quality. Because we found that our treatment can lead to the maturation of dendritic cells, immunotherapy can move to local treatment to more systemic treatment based on immune memory.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/07/160701093935.htm Original web page at Science Daily

Categories
News

* Imaging study in mice sheds light on how the brain draws a map to a destination

Columbia scientists have uncovered a key feature of the brain’s GPS that helps a mouse find what it is seeking. The study enabled scientists to define the precise duties of cells in a particular region of the hippocampus, the brain’s learning and memory center. The research also advances a long-standing quest in the field of neuroscience: tracing the pathway that information takes while traveling through the brain.

The authors announced these findings in the journal Neuron. “In this study, our goal was to simulate what our brains do as we walk aimlessly down the street, versus how our brains behave when looking for a specific address,” said Attila Losonczy, MD, PhD, a principal investigator at Columbia’s Mortimer B. Zuckerman Mind Brain Behavior Institute, associate professor of neuroscience at Columbia University Medical Center (CUMC) and the paper’s senior author. “By using the powerful two-photon microscope, we were able to observe the activity of individual cells in the mouse hippocampus, and then link that activity to a specific behavior — in this case, navigation — a technological feat that would have been impossible just a few years ago.”

The hippocampus can be divided into distinct areas that form an interconnected circuit through which memory-related information is processed. For this study, Dr. Losonczy and his team focused on the hippocampus’ main output node, area CA1, which was discovered by scientists to encode one’s location — work that was awarded the 2014 Nobel Prize.

“We’ve known that CA1 can be divided into two distinct sublayers of cells: the deep and superficial sublayers,” said Nathan Danielson, a doctoral candidate in neuroscience at CUMC and the paper’s first author. “Scientists have wondered whether this division was an indication that these two sublayers actually served different purposes in learning and memory. But no one had tested it, so we decided to look.”

To study these cells, the researchers placed mice on treadmills that had distinct colors, textures and smells while a two-photon microscope monitored the cellular activity in the CA1. The mice then performed two tasks.

In the first, mice ran on a treadmill while experiencing different sights and sounds, some familiar and others new. In the second, mice were given the task of finding a water reward placed at a specific, unmarked location along the treadmill. The team repeated these experiments over the course of several sessions and monitored how each of the sublayers responded to the different types of learning.

When the mice performed the first task, cells in the superficial sublayer of CA1 appeared to create an internal map that remained largely unchanged from session to session. By contrast, cells in the deep sublayer formed an internal map that was far more dynamic — in effect redrawing a different version of the map during each session.

During the second task, however, when the mice needed to learn the location of the hidden reward, the maps in the deep sublayer were significantly more stable, and less dynamic, than in the first task. The scientists also found that deep-sublayer activity was closely linked to the animal’s ability to find the reward. This distinction between the sublayers, the authors argue, could signify two different processes important for navigation.

“If you’re walking down the street looking for something specific — say, your favorite restaurant — your brain first needs a map of the neighborhood in general,” said Danielson. But to find that particular restaurant, he continued, the brain also assigns importance, or salience, to that specific location.

“In a sense, it’s the brain’s way of marking a location on a map with a giant X,” Danielson said. “So as you look for that restaurant, you need both the map and the X. Our findings suggest that, in the brain, these distinct types of information could be conveyed by the CA1’s distinct sublayers.”

“And if one month later you wanted to visit somewhere new, the deep sublayer would update the map, effectively marking the spot of the new location, while the underlying map of the neighborhood, created by the superficial sublayer, would remain relatively unchanged,” added Dr. Losonczy.

For Dr. Losonczy, this study speaks to the ingenious way that the brain’s underlying architecture allows it to accomplish a specific type of navigation.

“It’s astounding that the ability to navigate to a desired location, an enormously complex feat, can be represented so precisely in the structure of the hippocampus,” he said. “And it’s even more astounding that we can now witness it happening in real time.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160707131127.htm Original web page at Science Daily

Categories
News

Pituitary tissue grown from human stem cells releases hormones in rats

Researchers have successfully used human stem cells to generate functional pituitary tissue that secretes hormones important for the body’s stress response as well as for its growth and reproductive functions. When transplanted into rats with hypopituitarism–a disease linked to dwarfism and premature aging in humans–the lab-grown pituitary cells promoted normal hormone release. The study, which lays the foundation for future preclinical work, appears June 14 in Stem Cell Reports, a publication of the International Society for Stem Cell Researchers.

“The current treatment options for patients suffering from hypopituitarism, a dysfunction of the pituitary gland, are far from optimal,” says first study author Bastian Zimmer of the Sloan Kettering Institute for Cancer Research. “Cell replacement could offer a more permanent therapeutic option with pluripotent stem cell-derived hormone-producing cells that functionally integrate and respond to positive and negative feedback from the body. Achieving such a long-term goal may lead to a potential cure, not only a treatment, for those patients.”

The pituitary gland is the master regulator of hormone production in the body, releasing hormones that play a key role in bone and tissue growth, metabolism, reproductive functions, and the stress response. Hypopituitarism can be caused by tumors, genetic defects, brain trauma, immune and infectious diseases, or radiation therapy. The consequences of pituitary dysfunction are wide ranging and particularly serious in children, who can suffer severe learning disabilities, growth and skeletal problems, as well as effects on puberty and sexual function.

Currently, patients with hypopituitarism must take expensive, lifelong hormone replacement therapies that poorly mimic the body’s complex patterns of hormone secretion that fluctuates with circadian rhythms and responds to feedback from other organs. By contrast, cell replacement therapies hold promise for permanently restoring natural patterns of hormone secretion while avoiding the need for costly, lifelong treatments.

Recently, scientists developed a procedure for generating pituitary cells from human pluripotent stem cells–an unlimited cell source for regenerative medicine–using organoid cultures that mimic the 3D organization of the developing pituitary gland. However, this approach is inefficient and complicated, relies on ill-defined cellular signals, lacks reproducibility, and is not scalable or suitable for clinical-grade cell manufacturing.

To address these limitations, Zimmer and senior study author Lorenz Studer of the Sloan Kettering Institute for Cancer Research developed a simple, efficient, and robust stem cell-based strategy for reliably producing a large number of diverse, functional pituitary cell types suitable for therapeutic use. Instead of mimicking the complex 3D organization of the developing pituitary gland, this approach relies on the precisely timed exposure of human pluripotent stem cells to a few specific cellular signals that are known to play an important role during embryonic development.

Exposure to these proteins triggered the stem cells to turn into different types of functional pituitary cells that released hormones important for bone and tissue growth (i.e., growth hormone), the stress response (i.e., adrenocorticotropic hormone), and reproductive functions (i.e., prolactin, follicle-stimulating hormone, and luteinizing hormone). Moreover, these stem cell-derived cells released different amounts of hormone in response to known feedback signals generated by other organs in the body.

To test the therapeutic potential of this approach, the researchers transplanted the stem cell-derived pituitary cells under the skin of rats whose pituitary gland had been surgical removed. The cell grafts not only secreted adrenocorticotropic hormone, prolactin, and follicle-stimulating hormone, but they also triggered appropriate hormonal responses in the kidneys.

The researchers were also able to control the relative composition of different hormonal cell types simply by exposing human pluripotent stem cells to different ratios of two proteins: fibroblast growth factor 8 and bone morphogenetic protein 2. This finding suggests their approach could be tailored to generate specific cell types for patients with different types of hypopituitarism. “For the broad application of stem cell-derived pituitary cells in the future, cell replacement therapy may need to be customized to the specific needs of a given patient population,” Zimmer says.

In future studies, the researchers plan to further improve the protocol to generate pure populations of various hormone-releasing cell types, enabling the production of grafts that are tailored to the needs of individual patients. They will also test this approach on more clinically relevant animal models that have pituitary damage caused by radiation therapy and receive grafts in or near the pituitary gland rather than under the skin. This research could have important implications for cancer survivors, given that hypopituitarism is one of the main causes of poor quality of life after brain radiation therapy.

“Our findings represent a first step in treating hypopituitarism, but that does not mean the disease will be cured permanently within the near future,” Zimmer says. “However, our work illustrates the promise of human pluripotent stem cells as it presents a direct path toward realizing the promise of regenerative medicine for certain hormonal disorders.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/06/160614133606.htm Original web page at Science Daily

Categories
News

* Stem cells for Snoopy: pet medicines spark a biotech boom

Many pets are treated like family members — and that is often reflected in the veterinary care that they receive.

Little Jonah once radiated pain. The 12-year-old Maltese dog’s body was curled and stiff from the effort of walking with damaged knees. But after Kristi Lively, Jonah’s veterinary surgeon, enrolled him in a clinical trial of a therapeutic antibody to treat pain, his owner returned to the Village Veterinary Medical Center in Farragut, Tennessee, with tears in her eyes. Her tiny companion trotted easily alongside her. “I got my dog back,” she said.

Such cutting-edge treatments were once reserved for humans. But in recent years, the changing nature of pet ownership has sparked a boom in sophisticated therapies for animals — and many are now approaching the market. On 9 June, the company that sponsored the antibody trial, Nexvet of Dublin, presented its results at the American College of Veterinary Internal Medicine Forum in Denver, Colorado. Other companies are working on bone-marrow transplants, sophisticated cell therapies and cancer vaccines.

“When I was a child and just wanted to be a veterinarian, certainly I didn’t imagine I’d be doing what I’m doing now,” says Heather Wilson-Robles, a veterinary oncologist at Texas A&M University in College Station, who is engineering canine immune cells to fight cancer.

Cancer, arthritis and other diseases associated with old age are becoming more common as pets live longer, thanks in part to better treatment by their owners. “A generation ago, as beloved as Snoopy was, he lived in the backyard in the doghouse,” says Steven St. Peter, president of Aratana Therapeutics, a pet-therapy company in Leawood, Kansas. Now, pets are considered family members, often sharing beds with owners who are willing to pay hefty veterinary bills.

Many standard pet treatments are human drugs given at lower doses to account for animals’ smaller size. But antibodies and cell therapies generally cannot be used across species without provoking an unwanted immune response. And some human treatments simply will not work in pets: many common pain medications are toxic to cats.

Nexvet, which has raised more than US$80 million from investors since it was founded in 2011, takes antibodies that have been approved as human medicines and alters their structures to make them effective in cats or dogs. Moving from a drug lead to safety testing takes about 18 months, says chief executive Mark Heffernan, who estimates that Nexvet’s antibody therapies for pain will cost around $1,500 a year. The company is now looking into developing antibodies that block a protein called PD-1, thereby unleashing the immune system to fight cancer. This approach has shown tremendous promise for treating cancer in people.

Aratana is also developing antibody therapies for pets, and has applied for regulatory approval of a cancer vaccine that uses a bacterium to target malignant cells. The company hopes to move into cell therapies, and to develop a way to manufacture stem cells from fat for use against joint pain. St. Peter wants his company to be the first to win approval from the US Food and Drug Administration for a stem-cell therapy — ahead of firms developing such treatments for people.

Other forms of cell therapy could also result in new veterinary remedies. Last July, veterinary oncologist Colleen O’Connor founded a cancer-treatment company in Houston, Texas, called CAVU Biotherapies. To treat lymphoma, CAVU aims to isolate a sick dog’s immune cells, rejuvenate them in culture, and then infuse them back into the dog’s blood to stimulate an immune response. O’Connor used a similar approach in 2011 to treat Dakota, a bichon frise that belonged to then-US Senator Kent Conrad (Democrat, North Dakota). The dog, a Capitol Hill fixture known as the ‘101st senator’, entered remission but later died of cancer.

For many pet owners, cost is no object. Steven Suter, a veterinary oncologist at North Carolina State University in Raleigh, runs a bone-marrow transplant clinic for dogs that claims to cure 33% of lymphomas. Suter’s clinic was booked solid after it opened in 2008, despite offering treatment that can cost a dog owner up to $24,000. Still, Suter has worked to drive down the cost of care: to filter stem cells from blood, his clinic uses second-hand machines that were donated by a physician with a soft spot for schnauzers. Earlier this year, several major pet-insurance companies added bone-marrow transplants to the lists of procedures that they will pay for.

But when it comes to the latest pet treatments, some animals might be more equal than others. Cats are “physiologically finicky”, Suter says, noting that they may be too small to allow bone-marrow transplants using his usual machines. And O’Connor notes that cats’ immune systems also differ wildly from those of both humans and dogs — meaning that more basic research must be done before sophisticated immunotherapies can be deployed against feline ailments.

At Lively’s clinic, many dog and cat owners were grateful that their animals could participate in Nexvet’s clinical trial. But about a month after the trial ended, the effects of the antibody therapy began to fade. Jonah’s owner was among the clients who called Lively, desperate for a way to access the treatment again. “It’s tough,” Lively says. “They’ll have to wait until this product comes to market.”

Nature 534, 303–304 (16 June 2016) doi:10.1038/534303a

http://www.nature.com/ Nature

http://www.nature.com/news/stem-cells-for-snoopy-pet-medicines-spark-a-biotech-boom-1.20087 Original web page at Nature

Categories
News

* Researchers first to grow living bone that replicates original anatomical structure

A new technique developed by Gordana Vunjak-Novakovic, the Mikati Foundation Professor of Biomedical Engineering at Columbia Engineering and professor of medical sciences (in Medicine) at Columbia University, repairs large bone defects in the head and face by using lab-grown living bone, tailored to the patient and the defect being treated. This is the first time researchers have grown living bone that precisely replicates the original anatomical structure, using autologous stem cells derived from a small sample of the recipient’s fat. The study is published today in Science Translational Medicine.

“We’ve been able to show, in a clinical-size porcine model of jaw repair, that this bone, grown in vitro and then implanted, can seamlessly regenerate a large defect while providing mechanical function,” says Vunjak-Novakovic, who is also the director of Columbia’s Laboratory for Stem Cells and Tissue Engineering, co-director of the Craniofacial Regeneration Center, and director of the Bioreactor Core of the NIH Tissue Engineering Center. “The need is huge, especially for congenital defects, trauma, and bone repair after cancer surgery. The quality of the regenerated tissue, including vascularization with blood perfusion, exceeds what has been achieved using other approaches. So this is a very exciting step forward in improving regenerative medicine options for patients with craniofacial defects, and we hope to start clinical trials within a few years.”

Vunjak-Novakovic’s team, which included researchers from Columbia Engineering’s Department of Biomedical Engineering, Columbia’s College of Dental Medicine, Louisiana State University, and Tulane University School of Medicine, fabricated a scaffold and bioreactor chamber based on images of the weight-bearing jaw defect, to provide a perfect anatomical fit. The scaffold they built enabled bone formation without the use of growth factors, and also provided mechanical function, both of which are unique advantages for clinical application. They then isolated the recipient’s own stem cells from a small fat aspirate and, in just three weeks, formed the bone within a scaffold made from bone matrix, in a custom-designed perfused bioreactor. To mimic the logistics of envisioned clinical applications, where the patient and the bone manufacturing are at remote locations far from each other, the researchers shipped the bioreactor with the living bone across the country to be implanted.

An unexpected outcome was that the lab-grown bone, when implanted, was gradually replaced by new bone formed by the body, a result not seen with the implantation of a scaffold alone, without cells. “Our lab-grown living bone serves as an ‘instructive’ template for active bone remodeling rather than as a definitive implant,” says Vunjak-Novakovic. “This feature is what makes our implant an integral part of the patient’s own bone, allowing it to actively adapt to changes in the body throughout its life.”

Vunjak-Novakovic and her team are now including a cartilage layer in the bioengineered living bone tissue to study bone regeneration in complex defects of the head and face. They are also advancing their technology through advanced preclinical trials, and in planning stages with the FDA for clinical trials, through her company epiBone.

“Having a chance to work on innovative research that may be part of our future is intriguing, energizing, and really inspiring,” says the study’s lead author Sarindr Bhumiratana PhD’12, who also is chief scientific officer at epiBone.

“Today, tissue engineering is truly changing the way we approach tissue repair, drug testing, disease modeling,” Vunjak-Novakovic adds. “In all these diverse areas, we now can put the cells to work for us and make tissues, by providing bioengineered environments that mimic their native milieu.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160615151711.htm Original web page at Science Daily

Categories
News

Human brain houses diverse populations of neurons, new research shows

A team of researchers has developed the first scalable method to identify different subtypes of neurons in the human brain. The research lays the groundwork for “mapping” the gene activity in the human brain and could help provide a better understanding of brain functions and disorders, including Alzheimer’s, Parkinson’s, schizophrenia and depression.

By isolating and analyzing the nuclei of individual human brain cells, researchers identified 16 neuronal subtypes in the cerebral cortex — the brain’s outer layer of neural tissue responsible for cognitive functions including memory, attention and decision making. The team, led by researchers at the University of California San Diego, The Scripps Research Institute (TSRI) and Illumina, published their findings in the June 24 online issue of the journal Science.

“We’re providing a unified framework to look at and compare individual neurons, which can help us find out how many unique types of neurons exist,” said Kun Zhang, bioengineering professor at the University of California, San Diego and a corresponding author of the study.

Researchers can use these different neuronal subtypes to build what Zhang calls a “reference map” of the human brain — a foundation to understand the differences between a healthy brain and a diseased brain.

“In the future, patients with brain disorders or abnormalities could be diagnosed and treated based on how they differ from the reference map. This is analogous to what’s being done with the reference human genome map,” Zhang said.

The new study reflects a growing understanding that individual brain cells are unique: they express different types of genes and perform different functions. To better understand this diversity, researchers analyzed more than 3,200 single human neurons in six Brodmann areas, which are regions of the cerebral cortex classified by their functions and arrangements of neurons.

Through an interdisciplinary collaborative effort, the team developed a new method to isolate and sequence individual cell nuclei. TSRI researchers led by neuroscience professor Jerold Chun obtained the samples from a post mortem brain and focused on isolating the neuronal nuclei. Zhang’s lab worked with Fluidigm, a manufacturer of microfluidic chips for single-cell studies, to develop a protocol to identify and quantify RNA molecules in individual neuronal nuclei. Scientists at San Diego-based Illumina sequenced the resulting RNA libraries. Researchers led by biochemistry professor Wei Wang at UC San Diego developed algorithms to cluster and identify 16 neuronal subtypes from the sequenced datasets.

Researchers deciphered what types of genes were “turned on” within each nucleus and revealed that various combinations of the 16 subtypes tended to cluster in cortical layers and Brodmann areas, helping explain why these regions look and function differently.

Neurons exhibited many differences in their transcriptomic profiles — the patterns of genes that are being actively expressed by these cells — revealing single neurons with shared, as well as unique, characteristics that likely lead to difference in cellular function.

“We’re finding new ways to understand the basic building blocks of the brain,” said Blue Lake, a postdoctoral researcher in Zhang’s lab and a co-first author of the study. “Our study opens the door to look at global gene expression patterns and how that defines cell types within a normal tissue, which can also be used to see what’s abnormal in terms of disease or disorders.”

In future studies, researchers aim to analyze neurons in other Brodmann areas of the brain and investigate what subtypes exist in other brain regions. They also plan to study neurons from multiple post mortem human brains (this study only involved one) to investigate neuronal diversity among individuals.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160623150111.htm  Original web page at Science Daily

Categories
News

* Improving cell transplantation after spinal cord injury: When, where and how?

Spinal cord injuries are mostly caused by trauma, often incurred in road traffic or sporting incidents, often with devastating and irreversible consequences, and unfortunately having a relatively high prevalence (250,000 patients in the USA; 80% of cases are male). One currently explored approach to restoring function after spinal cord injury is the transplantation of olfactory ensheathing cells (OECs) into the damaged area. The hope is that these will encourage the repair of damaged neurons, but does it work? And if so, how can it be optimized?

According to a systematic analysis of the literature published this week in PLOS Biology, after experimental spinal cord injury, transplanting OECs into the site of damage does indeed significantly improve locomotor performance. To reach this conclusion, Ralf Watzlawick, Jan Schwab, and their colleagues at the Ohio State University Wexner Medical Center, Charité Universtaetsmedizin Berlin and the CAMARADES consortium (Collaborative Approach to Meta Analysis and Review of Animal Data from Experimental Studies), analyzed 49 studies, published between 1949 and 2014, which included 62 experiments involving 1164 animals.

Restoration of function after spinal cord injury remains one of the most formidable challenges in regenerative medicine, but cell transplantation into the spinal cord represents a promising treatment strategy. OECs are considered particularly suitable for transplantation because they have been shown to be neuro-protective and to promote neuro-regeneration in different settings, and can be extracted from the patient’s own nasal cavity, thereby minimizing the chances of graft rejection and avoiding the need for immunosuppressive drugs.

However, reports in the literature about the efficacy of transplantation of OECs for treatment of spinal cord injury have been contradictory. Therefore, to investigate the in vivo evidence for the efficacy of this procedure, the authors implemented a systematic review and meta-analysis of the literature. Importantly, the authors set out to explore the potential influence of variations in experimental approaches and unreported data.

“We felt that after more than two decades since the discovery that OECs elicit effects on neural plasticity in vivo, it was time to test their effects by appropriate methodology beyond reproduction,” the authors argued.

The data analysed by the authors justify the use of OECs as a cellular substrate to develop and to optimize minimally invasive and secure protocols for repairing damaged spinal cord. They also identified several aspects of the cell transplantation procedure that could have a significant impact on the size of the therapeutic effect, including: the time-point of application, the use of surgical micro-dissection to “refresh” the scar tissue, the localization of transplanted cells, the number of injections, the injected volume, and the dose of cells administered.

Importantly, by using state-of-the-art statistical methods the authors also found that the impact of publication bias (due to selective failure to report results) was minimal, further supporting the translational potential of this approach.

Despite being focussing on OECs, the findings may be of more general relevance for optimizing the transplantation of other cell types after spinal cord injury.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160531165224.htm  Original web page at Science Daily

 

Categories
News

Genetic code of red blood cells discovered

Eight days. That’s how long it takes for skin cells to reprogram into red blood cells. Researchers at Lund University in Sweden, together with colleagues at Center of Regenerative Medicine in Barcelona, have successfully identified the four genetic keys that unlock the genetic code of skin cells and reprogram them to start producing red blood cells instead.

“We have performed this experiment on mice, and the preliminary results indicate that it is also possible to reprogram skin cells from humans into red blood cells. One possible application for this technique is to make personalised red blood cells for blood transfusions, but this is still far from becoming a clinical reality,” says Johan Flygare, manager of the research group and in charge of the study.

Every individual has a unique genetic code, which is a complete instruction manual describing exactly how all the cells in the body are formed. This instruction manual is stored in the form of a specific DNA sequence in the cell nucleus. All human cells — brain, muscle, fat, bone and skin cells — have the exact same code. The thing that distinguishes the cells is which chapter of the manual the cells are able to read. The research group in Lund wanted to find out how the cells open the chapter that contains instructions on how to produce red blood cells. The skin cells on which the study was based had access to the instruction manual, but how were the researchers able to get them to open the chapter describing red blood cells?

With the help of a retrovirus, they introduced different combinations of over 60 genes into the skin cells’ genome, until one day they had successfully converted the skin cells into red blood cells. The study is published in the scientific journal Cell Reports.

“This is the first time anyone has ever succeeded in transforming skin cells into red blood cells, which is incredibly exciting,” says Sandra Capellera, doctoral student and lead author of the study.

The study shows that out of 20,000 genes, only four are necessary to reprogram skin cells to start producing red blood cells. Also, all four are necessary in order for it to work.

“It’s a bit like a treasure chest where you have to turn four separate keys simultaneously in order for the chest to open,” explains Sandra.

The discovery is significant from several aspects. Partly from a biological point of view — understanding how red blood cells are produced and which genetic instructions they require — but also from a therapeutic point of view, as it creates an opportunity to produce red blood cells from the skin cells of a patient. There is currently a lack of blood donors for, for instance, patients with anemic diseases. Johan Flygare explains:

“An aging population means more blood transfusions in the future. There will also be an increasing amount of people coming from other countries with rare blood types, which means that we will not always have blood to offer them.”

Red blood cells are the most common cells in the human body, and are necessary in order to transport oxygen and carbon dioxide. Millions of people worldwide suffer from anemia — a condition in which the patient has an insufficient amount of red blood cells. Patients with chronic anemia are among the most problematic cases. They receive regular blood transfusions from different donors, which can eventually lead to the patient developing a reaction to the new blood. They simply become allergic to the donor’s blood. Finding a feasible way to make blood from an individual’s own skin cells would bring relief to this group of patients. However, further studies on how the generated blood performs in living organisms are needed.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160602132638.htm Original web page at Science Daily

Categories
News

Mobilizing mitochondria may be key to regenerating damaged neurons

Researchers at the National Institute of Neurological Disorders and Stroke have discovered that boosting the transport of mitochondria along neuronal axons enhances the ability of mouse nerve cells to repair themselves after injury. The study, “Facilitation of axon regeneration by enhancing mitochondrial transport and rescuing energy deficits,” which has been published in The Journal of Cell Biology, suggests potential new strategies to stimulate the regrowth of human neurons damaged by injury or disease.

Neurons need large amounts of energy to extend their axons long distances through the body. This energy — in the form of adenosine triphosphate (ATP) — is provided by mitochondria, the cell’s internal power plants. During development, mitochondria are transported up and down growing axons to generate ATP wherever it is needed. In adults, however, mitochondria become less mobile as mature neurons produce a protein called syntaphilin that anchors the mitochondria in place. Zu-Hang Sheng and colleagues at the National Institute of Neurological Disorders and Stroke wondered whether this decrease in mitochondrial transport might explain why adult neurons are typically unable to regrow after injury.

Sheng and his research fellow Bing Zhou, the first author of the study, initially found that when mature mouse axons are severed, nearby mitochondria are damaged and become unable to provide sufficient ATP to support injured nerve regeneration. However, when the researchers genetically removed syntaphilin from the nerve cells, mitochondrial transport was enhanced, allowing the damaged mitochondria to be replaced by healthy mitochondria capable of producing ATP. Syntaphilin-deficient mature neurons therefore regained the ability to regrow after injury, just like young neurons, and removing syntaphilin from adult mice facilitated the regeneration of their sciatic nerves after injury.

“Our in vivo and in vitro studies suggest that activating an intrinsic growth program requires the coordinated modulation of mitochondrial transport and recovery of energy deficits. Such combined approaches may represent a valid therapeutic strategy to facilitate regeneration in the central and peripheral nervous systems after injury or disease,” Sheng says.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/06/160607151233.htm Original web page at Science Daily

Categories
News

* How brain connects memories across time

Neuroscientists boost ability of aging brain to recapture links between related memories. Using a miniature microscope that opens a window into the brain, UCLA neuroscientists have identified in mice how the brain links different memories over time. While aging weakens these connections, the team devised a way for the middle-aged brain to reconnect separate memories.

The findings, which were published in the advance online edition of Nature, suggest a possible intervention for people suffering from age-related memory problems.

“Until now, neuroscientists have focused on how the brain creates and stores single memories,” said principal investigator Alcino Silva, a professor of neurobiology at the David Geffen School of Medicine at UCLA. “We wanted to explore how the brain links two memories and whether the passage of time affects the strength of the connection.”

“In the real world, memories don’t happen in isolation,” said first author Denise Cai, a researcher in Silva’s lab. “Our past experiences influence the creation of new memories and help us predict what to expect and make informed decisions in the future.”

In an intricate experiment, the UCLA team tested in young and middle-aged mice whether the brain linked memories of experiences separated by five hours versus seven days.

The lab used a miniature microscope, called a Miniscope, which was developed by UCLA neuroscientists Dr. Peyman Golshani, Baljit Khakh and Silva with funding from the presidential BRAIN Initiative and the Geffen School. The instrument’s powerful camera allowed the scientists to peer into the brains of young and observe their cells in action. The tiny, head-mounted microscope illuminated the animals’ neurons firing as the mice moved freely in their natural environments.

For 10 minutes at a time, each mouse was placed in three boxes, all unique in terms of fragrance, shape, lighting and flooring. A week’s time separated placement in the first and second boxes. Only five hours separated time spent in the second and third boxes, where the mouse later received a small shock to the foot.

Two days later, the team returned each mouse to all three boxes. As expected, the mice froze with fear when it recognized the inside of the third box.

“The mouse also froze in the second box, where no shock occurred,” Silva observed. “This suggests that the mouse transferred its memory of the shock in the third box to its experience in the second box five hours earlier.”

When Silva and Cai examined the animals’ brains, the neural activity confirmed their hypothesis.

“The same brain cells that recorded the mouse’s shock in the third box also encoded its memory of the second box a few hours earlier,” Cai said. “We saw 20 percent more overlap in the neural circuits that recorded the animal’s experiences in the memories that unfolded closer in time.”

In other words, says Silva, “The memories became interrelated in how they were encoded and stored by the brain, such that the recall of one memory triggered the recall of another memory related in time.”

Based on an earlier Silva finding, the team knew that a cell is most likely to encode a memory when it’s aroused and ready to fire. Neuroscientists refer to this condition as excitability.

“The excitable brain is already warmed up,” Silva said. “It’s like stretching your muscles before exercise or revving your car engine before you drive.”

Suspecting that aging weakens neurons’ ability to fully excite, the UCLA researchers conducted a similar experiment in middle-aged mice. They introduced each of the mice to two boxes, five hours apart, and administered a foot shock in the second box.

When they returned the animals to the boxes two days later, the results could not have been more clear-cut.

“The older mice froze only in the box where they had received a shock,” Cai explained. “They did not react in the first box.”

A glimpse into the Miniscopes confirmed that the brains of the mice did not connect the two memories; each memory was encoded on its own neural circuit.

Next the team focused on boosting the older animals’ ability to link memories. Cai used a biological tool to excite neurons in a tiny part of the hippocampus — the memory center of the brain — before introducing the mice to the first box.

She stimulated the same cells before placing the mice in the first box and the second box, where they received a foot shock two days later.

“The proof in the pudding arrived when we reintroduced the middle-aged mice to the first box,” Silva said. “The animals froze — they now linked the shock that happened in the second box to the first. This suggests that increased excitability had reversed their age-related inability to link memories.”

Cai and Silva are currently testing an FDA-approved drug’s effect on the ability of middle-aged mice to connect memories.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160523113730.htm Original web page at Science Daily

Categories
News

* Stem cells from diabetic patients coaxed to become insulin-secreting cells

If damaged cells are replaceable, type 1 diabetics wouldn’t need insulin shots.

Signaling a potential new approach to treating diabetes, researchers at Washington University School of Medicine in St. Louis and Harvard University have produced insulin-secreting cells from stem cells derived from patients with type 1 diabetes.

People with this form of diabetes can’t make their own insulin and require regular insulin injections to control their blood sugar. The new discovery suggests a personalized treatment approach to diabetes may be on the horizon — one that relies on the patients’ own stem cells to manufacture new cells that make insulin.

The researchers showed that the new cells could produce insulin when they encountered sugar. The scientists tested the cells in culture and in mice, and in both cases found that the cells secreted insulin in response to glucose.

“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,” said first author Jeffrey R. Millman, PhD, an assistant professor of medicine and of biomedical engineering at Washington University School of Medicine. “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.”

Millman, whose laboratory is in the Division of Endocrinology, Metabolism and Lipid Research, began his research while working in the laboratory of Douglas A. Melton, PhD, Howard Hughes Medical Institute investigator and a co-director of Harvard’s Stem Cell Institute. There, Millman had used similar techniques to make beta cells from stem cells derived from people who did not have diabetes. In these new experiments, the beta cells came from tissue taken from the skin of diabetes patients.

“There had been questions about whether we could make these cells from people with type 1 diabetes,” Millman explained. “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.”

Millman said more research is needed to make sure that the beta cells made from patient-derived stem cells don’t cause tumors to develop — a problem that has surfaced in some stem cell research — but there has been no evidence of tumors in the mouse studies, even up to a year after the cells were implanted.

He said the stem cell-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.

The idea of replacing beta cells isn’t new. More than two decades ago, Washington University researchers Paul E. Lacy, MD, PhD, now deceased, and David W. Scharp, MD, began transplanting such cells into patients with type 1 diabetes. Still today, patients in several clinical trials have been given beta cell transplants with some success. However, those cells come from pancreas tissue provided by organ donors. As with all types of organ donation, the need for islet beta cells for people with type 1 diabetes greatly exceeds their availability.

Millman said that the new technique also could be used in other ways. Since these experiments have proven it’s possible to make beta cells from the tissue of patients with type 1 diabetes, it’s likely the technique also would work in patients with other forms of the disease — including type 2 diabetes, neonatal diabetes and Wolfram syndrome. Then it would be possible to test the effects of diabetes drugs on the beta cells of patients with various forms of the disease.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160510132809.htm  Original web page at Science Daily

Categories
News

Zika virus may cause microcephaly by hijacking human immune molecule

The U.S. Centers for Disease Control and Prevention recently concluded that Zika virus infection in pregnant women can stunt neonatal brain development, leading to babies born with abnormally small heads, a condition known as microcephaly. Now, for the first time, researchers at University of California San Diego School of Medicine have determined one way Zika infection can damage developing brain cells. The study, published May 6, 2016 in Cell Stem Cell, also shows that inhibiting this mechanism reduces brain cell damage, hinting at a new therapeutic approach to mitigating the effects of prenatal Zika virus infection.

Using a 3D, stem cell-based model of a first-trimester human brain, the team discovered that Zika activates TLR3, a molecule human cells normally use to defend against invading viruses. In turn, hyper-activated TLR3 turns off genes that stem cells need to specialize into brain cells and turns on genes that trigger cell suicide. When the researchers inhibited TLR3, brain cell damage was reduced in this organoid model.

“We all have an innate immune system that evolved specifically to fight off viruses, but here the virus turns that very same defense mechanism against us,” said senior author Tariq Rana, PhD, professor of pediatrics at UC San Diego School of Medicine. “By activating TLR3, the Zika virus blocks genes that tell stem cells to develop into the various parts of the brain. The good news is that we have TLR3 inhibitors that can stop this from happening.”

In the study, Rana’s team first made sure their organoid model was truly representative of the early developing human brain. They found that the model’s stem cells differentiate (specialize) into the various cells of the brain in the same way that they do in the first trimester of human development. The researchers also compared patterns of gene activation in organoid cells to a database of human brain genetic information. They found that, genetically speaking, their organoid model closely resembled fetal brain tissue at eight to nine weeks post-conception.

When the team added a prototype Zika virus strain to the 3D brain model, the organoid shrank. Five days after the infection, healthy, mock-infected brain organoids had grown an average of 22.6 percent. In contrast, the Zika-infected organoids had decreased in size by an average 16 percent.

Rana’s team also noticed that the TLR3 gene was activated in the Zika virus-infected organoids. TLR3 is a protein found both inside and attached to the outside of cells. TLR3’s only job is to act as an antenna, sensing double-stranded RNA specific to viruses. When viral RNA binds TLR3, it kicks off an immune response. To do that, TLR3 helps activate many different genes that aid in fighting an infection. However, in developing brain cells, the researchers found TLR3 activation also influences 41 genes that add up to a double whammy in this model — diminished stem cell differentiation into brain cells and increased cell suicide, a carefully controlled process known as apoptosis.

To determine whether TLR3 activation could be the cause of Zika-induced organoid shrinkage — and therefore perhaps microcephaly — or merely a symptom of it, Rana’s team treated some of the infected organoids with a TLR3 inhibitor. They found that the TLR3 inhibitor significantly tempered Zika virus’ severe effects on brain cell health and organoid size, underscoring TLR3’s role linking infection and brain damage. However, the treated organoids weren’t perfect. As evidenced by their non-smooth outer surfaces, infected but treated organoids still encountered more cell death and disruption than uninfected organoids.

While promising, this research has been conducted only in human and mouse cells growing in the laboratory thus far. In addition, the Zika virus strain used in this study (MR766) originated in Uganda, while the current Zika outbreak in Latin America involves a slightly different strain that originated in Asia.

“We used this 3D model of early human brain development to help find one mechanism by which Zika virus causes microcephaly in developing fetuses,” Rana said, “but we anticipate that other researchers will now also use this same scalable, reproducible system to study other aspects of the infection and test potential therapeutics.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160506132202.htm  Original web page at Science Daily

Categories
News

* Cells carry ‘memory’ of injury, which could reveal why chronic pain persists

A new study from King’s College London offers clues as to why chronic pain can persist, even when the injury that caused it has gone. Although still in its infancy, this research could explain how small and seemingly innocuous injuries leave molecular ‘footprints’ which add up to more lasting damage, and ultimately chronic pain.

All of us are likely to know someone who suffers from persistent pain — it is a very common condition, which can be caused by sports injuries, various diseases and the process of ageing. Treatment options are limited and doctors are often unable to offer anything more than partial relief with painkillers, leaving their patients resigned to suffering.

While chronic pain can have many different causes, the outcome is often the same: an overly sensitive nervous system which responds much more than it normally would. However, a question still remains as to why the nervous system should remain in this sensitive state over long periods of time, especially in instances where the underlying injury or disease has gone.

Researchers from King’s sought to answer this question by examining immune cells in the nervous system of mice, which are known to be important for the generation of persistent pain.

In the study, published today in Cell Reports, they found that nerve damage changes epigenetic marks on some of the genes in these immune cells. Epigenetics is the process that determines which gene is expressed and where. Some epigenetic signals have direct functional consequences, while others are just primers: flags that indicate a potential to act or be modified.

The cells examined in this King’s study still behaved as normal, but the existence of these novel epigenetic marks may mean that they carry a ‘memory’ of the initial injury.

Dr Franziska Denk, first author of the study, from the Wolfson Centre for Age Related Diseases at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN), King’s College London, said: ‘We are ultimately trying to reveal why pain can turn into a chronic condition. We already knew that chronic pain patients have nerves that are more active, and we think this is probably due to various proteins and channels in those nerves having different properties.

However, it is unclear why these nerves should remain in this overactive, highly sensitive state, even when the initial injury or disease has gone: the back pain from two years ago that never quite went away or the joints that are still painful despite your rheumatoid arthritis being in remission.’

Dr Denk added: ‘We want to know why these proteins and channels should maintain their altered function over such a long period of time. Cells have housekeeping systems by which the majority of their content are replaced and renewed every few weeks and months — so why do crucial proteins keep being replaced by malfunctioning versions of themselves? Our study is the very first step towards trying to answer this question by exploring the possibility that changes in chronic pain may persist because of epigenetics. We hope that future research in this area could help in the search for novel therapeutic targets.’

Professor Stephen McMahon from the IoPPN at King’s College London said: ‘This research raises many interesting questions: do neurons also acquire epigenetic footprints as a result of nerve injury? Do these molecular footprints affect the function of proteins? And are they ultimately the reason that chronic pain persists in patients over such long periods of time?

‘The last question is particularly hard to answer, because to study epigenetics we need access to pure cell populations. Obviously, many of these are only accessible in postmortem tissue. However, colleagues at King’s are already doing this in psychiatry, through studies such as the The PsychENCODE project, so it is possible.’

Dr Giovanna Lalli, Neuroscience & Mental Health Senior Portfolio Developer at the Wellcome Trust, which part-funded the study, said: ‘People develop chronic pain for a huge variety of reasons. We therefore need an equally diverse range of treatments to tackle the different root causes.

‘The clues from this study, suggesting epigenetic changes may be involved in pain persisting, will hopefully lead us to better understand the mechanisms underlying chronic pain.’

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160512124930.htm  Original web page at Science Daily

Categories
News

Targeted missiles against aggressive cancer cells

Targeted missiles that can enter cancer cells and deliver lethal cell toxins without harming surrounding healthy tissue. This has been a long-standing vision in cancer research, but it has proved difficult to accomplish. A research group at Lund University in Sweden has now taken some crucial steps in this direction.

“For several years, we tried to elucidate which target proteins on the cancer cells’ surface can be used to help these ‘missiles’ to gain entry into cells. Developing this method has been complicated, and we feel pleased to finally have succeeded,” says Professor of Clinical Oncology Mattias Belting. His research group recently published this new method in Nature Communications.

Mattias Belting describes the interior of a cancer tumour as a hostile environment. The rapid cell division of the tumour leads to oxygen deficiency, low pH levels, and nutrient deprivation. In this environment, some cells die spontaneously, while others can be destroyed with the help of radiation, chemo- or immunotherapy. However, the cells that adapt and survive are particularly aggressive.

“We call them stressed cells, and they are known to be more aggressive and insensitive to regular cancer treatments. These are the ones we must find new ways to fight against,” explains Mattias Belting.

The Lund researchers have mapped the thousands of proteins that exist on the surfaces of regular cancer cells, and cells that are stressed due to lack of oxygen. They also found a special protein (caveolin-1) that serves as a gatekeeper, and prevents many of the surface proteins from entering stressed cancer cells.

The researchers continued with identifying some 30 targeted proteins that exist in large quantities on the surfaces of stressed cancer cells, and which also have the ability to effectively pass the “gatekeeper” and be transported into the cells. Against one of these proteins, they have successfully managed to target a toxin-conjugated missile, in the form of an antibody connected to a certain cell toxin, which was able to enter and kill stressed cells, while leaving other cells unharmed.

“The most important aspect of our results is not only that we have identified the proteins that exist on the stressed cancer cells, but also which of them can be used as targets for delivering drugs into the cells,” says first author of the study Erika Bourseau-Guilmain.

There has already been considerable interest in the group’s research. Their method and some of the target proteins are described in detail in the article in Nature Communications, enabling other researchers to build on the foundation laid by the research group from Lund.

“We want to continue to study other target proteins that were identified. We are currently studying other types of stress to find additional, potential target proteins for drug development,” says Mattias Belting.

The Lund researchers worked with cells from e.g. glioblastoma — a type of brain tumour that is difficult to treat. However, they believe that the “missile method” can be used not only against this type, but against many, if not all, types of solid cancers, as stressed cancer cells exist in all types of aggressive tumours.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/04/160420090110.htm  Original web page at Science Daily

Categories
News

* Stem cell therapy reverses age-related osteoporosis in mice

Imagine telling a patient suffering from age-related (type-II) osteoporosis that a single injection of stem cells could restore their normal bone structure. This week, with a publication in STEM CELLS Translational Medicine, a group of researchers from the University of Toronto and The Ottawa Hospital suggest that this scenario may not be too far away.

Osteoporosis affects over 200M people worldwide and, unlike post-menopausal (type-I) osteoporosis, both women and men are equally susceptible to developing the age-related (type-II) form of this chronic disease. With age-related osteoporosis, the inner structure of the bone diminishes, leaving the bone thinner, less dense, and losing its function. The disease is responsible for an estimated 8.9 M fractures per year worldwide. Fractures of the hip–one of the most common breaks for those suffering from type-II osteoporosis–lead to a significant lack of mobility and, for some, can be deadly.

But how can an injection of stem cells reverse the ravages of age in the bones? Professor William Stanford, senior author of the study, had in previous research demonstrated a causal effect between mice that developed age-related osteoporosis and low or defective mesenchymal stem cells (MSCs) in these animals.

“We reasoned that if defective MSCs are responsible for osteoporosis, transplantation of healthy MSCs should be able to prevent or treat osteoporosis,” said Stanford, who is a Senior Scientist at The Ottawa Hospital and Professor at the University of Ottawa.

To test that theory, the researchers injected osteoporotic mice with MSCs from healthy mice. Stem cells are “progenitor” cells, capable of dividing and changing into all the different cell types in the body. Able to become bone cells, MSCs have a second unique feature, ideal for the development of human therapies: these stem cells can be transplanted from one person to another without the need for matching (needed for blood transfusions, for instance) and without being rejected.

After six months post-injection, a quarter of the life span of these animals, the osteoporotic bone had astonishingly given way to healthy, functional bone.

“We had hoped for a general increase in bone health,” said John E. Davies, Professor at the Faculty of Dentistry and the Institute of Biomaterials & Biomedical Engineering (IBBME) at the University of Toronto, and a co-author of the study. “But the huge surprise was to find that the exquisite inner “coral-like” architecture of the bone structure of the injected animals–which is severely compromised in osteoporosis–was restored to normal.”

The study could soon give rise to a whole new paradigm for treating or even indefinitely postponing the onset of osteoporosis. Currently there is only one commercially available therapy for type-II osteoporosis, a drug that maintains its effectiveness for just two years.

And, while there are no human stem cell trials looking at a systemic treatment for osteoporosis, the long-range results of the study point to the possibility that as little as one dose of stem cells might offer long-term relief.

“It’s very exciting,” said Dr. Jeff Kiernan, first author of the study. A graduate from IBBME who is beginning a Postdoctoral Fellowship at The Ottawa Hospital with the Centre for Transfusion Research, Kiernan pursued the research for his doctoral degree.

“We’re currently conducting ancillary trials with a research group in the U.S., where elderly patients have been injected with MSCs to study various outcomes. We’ll be able to look at those blood samples for biological markers of bone growth and bone reabsorption,” he added.

If improvements to bone health are observed in these ancillary trials, according to Stanford, larger dedicated trials could follow within the next 5 years.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/03/160317105629.htm  Original web page at Science Daily

Categories
News

* New hope for spinal cord injuries

Stem cells have been used successfully, for the first time, to promote regeneration after injury to a specialized band of nerve fibres that are important for motor function.

Researchers from Hokkaido University in Japan together with an international team of scientists implanted specialized embryonic stem cells into the severed spinal cords of rats. The stem cells, called neural progenitor cells, were taken from rat embryos and directed to develop as spinal cord tissue. The implants, or “grafts,” promoted extensive regeneration of the severed nerve fibres, with the rats showing improvement in their ability to move their forelimbs. The team also used grafts of human neural stem cells in injured rats with similar results, demonstrating the potential of the success of this method across species.

The corticospinal tract (CST) is a band of nerve fibres that travels from the brain, through the brain stem and into the spinal cord. This structure is very important for motor function in humans. Injuries to the CST can result in paralysis. Much research has been done, with some progress, on using stem cells to regenerate other bands of nerve fibres in the spinal cord. But these have involved small gaps between the severed nerves in the presence of bands of bridging tissue. Lesions to nerve fibres located in the CST, however, and those involving large gaps and no bands of bridging tissue have proven largely resistant to regeneration.

The success of this current trial, reported in Nature Medicine, is promising for the future treatment of humans with severe spinal cord injuries. But much work remains to be done before it can be translated into clinical treatments. Further research is required to determine the best cell type to be used for grafting and for establishing safe grafting methods.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/04/160415144520.htm  Original web page at Science Daily

Categories
News

Treating myasthenia gravis with autologous hematopoietic stem cell transplants

A report on seven cases of severe myasthenia gravis (an autoimmune disease characterized by severe muscle weakness) suggests that autologous hematopoietic stem cell transplantation (when a patient’s own stem cells are used) may result in long-term remission that is symptom and treatment free, according to an article published online by JAMA Neurology.

The study by Harold Atkins, M.D., F.R.C.P.C., of the University of Ottawa and the Ottawa Hospital, Canada, and coauthors reports outcomes at the Ottawa Hospital from 2001 through 2014.

All of the patients who were treated had persistent severe or life-threatening symptoms related to myasthenia gravis (MG), although they had used intensive immunosuppressive therapies.

“The ability to control autoimmunity by autologous HSCT [hematopoietic stem cell transplantation] has been demonstrated in other treatment-refractory autoimmune conditions, including neurologic diseases. … The role of autologous HSCT for MG warrants further exploration with prospective testing,” the authors conclude.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/04/160404133932.htm  Original web page at Science Daily