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April 2020

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Potential for cell replacement therapy — ScienceDaily

The loss of insulin-secreting beta cells by autoimmune destruction leads to type 1 diabetes. Clinical islet cell transplantation has the potential to cure diabetes, but donor pancreases are rare. In a new study, a group of researchers developed an improved pluripotent stem cell differentiation protocol to generate beta cells in vitro with superior glucose response and insulin secretion. This is a major step towards beta cell replacement therapy.

Human pluripotent stem cells (either human embryonic stem cells or induced pluripotent stem cells) can differentiate into every cell type of the human body with unlimited self-renewing capacity. Hence, pluripotent stem cells are an optimal source to generate specialized cell types for cell replacement therapy, e.g. beta cells for diabetic patients. However, current in vitro beta cell differentiation protocols are very complex due to the high number of differentiation steps. The process requires almost 20 signaling proteins and small molecules to regulate the growth and differentiation of the cells and lasts for more than four weeks. Within this multi-step process not all cells differentiate into the targeted cells but take wrong differentiation paths. This can lead to a highly heterogeneous cell population with beta cells which are not completely functional. A group of researchers at Helmholtz Zentrum München, the German Center for Diabetes Research (DZD), Technical University of Munich (TUM) and Miltenyi Biotec therefore tried to improve the quality of stem cell-derived beta cells.

CD177 quality control

The researchers developed an approach to enrich the stem cell culture with highly specialized pancreas progenitors which might lead to a more targeted differentiation into beta cells. “From developmental biology we knew that pancreatic progenitors are already specified at the endoderm stage — the first step of differentiation. We needed to find out if this was true also for human pluripotent stem cell differentiation,” explains Prof. Heiko Lickert, Director at the Institute of Diabetes and Regeneration Research at Helmholtz Zentrum München, Professor of Beta Cell Biology at TUM School of Medicine and member of the Research Coordination Board of the German Center for Diabetes Research (DZD).

To investigate on this, the researchers were looking for a possibility to better control the quality of the endoderm and its differentiation into specified pancreas progenitors. In a cooperation with Sebastian Knöbel’s group at Miltenyi Biotec they identified a monoclonal antibody called CD177 which marks a subpopulation of the endoderm that efficiently and homogenously differentiates into specified pancreatic progenitors. CD177 can therefore function as a quality control. “With CD177 we can already see at an early stage if the cells are on the right differentiation track. This can help save lots of time, efforts and money,” says Lickert.

Enriching the stem cell culture with CD177 at the endoderm stage increases the generation of specified pancreatic progenitors. Ultimately, this leads to more mature and more functional beta cells that respond better to glucose and show improved insulin secretion patterns.

Cell replacement therapy, disease modelling and drug screening

Current beta cell differentiation protocols generate very heterogeneous cell populations that not only contain beta cells, but also remaining pancreatic progenitors or cell types from a different lineage. The purification by CD177 will not only improve the homogeneity and quality of the generated beta cells but also increase their clinical safety, as pluripotent stem cells are separated out. This is a crucial step towards the clinical translation of stem cell-derived beta cell replacement therapy for patients with type 1 diabetes.

Furthermore, as CD177 generated beta cells are more similar to beta cells in the human body, the CD177 protocol will help to establish disease modeling systems that can mimic the human pancreas. In addition, a differentiation protocol giving rise to functional beta cells is of highest interest for drug screening approaches.

About this study

This study was a collaboration between Helmholtz Zentrum München, the German Center for Diabetes Research (DZD), Technical University of Munich (TUM) and Miltenyi Biotec. It was funded by the German Center for Diabetes Research (DZD), the EU consortium HumEN (“Up-scaling human insulin-producing beta cell production by efficient differentiation and expansion of pancreatic endoderm progenitors” — HEALTH.2013.1.4-1. Controlling differentiation and proliferation in human stem cells intended for therapeutic use. FP7-HEALTH-2013-INNOVATION-1) and the European Union’s Horizon 2020 research and innovation program under grant agreement number 874839.

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CRISPR corrects genetic defect so cells can normalize blood sugar — ScienceDaily

Using induced pluripotent stem cells produced from the skin of a patient with a rare, genetic form of insulin-dependent diabetes called Wolfram syndrome, researchers transformed the human stem cells into insulin-producing cells and used the gene-editing tool CRISPR-Cas9 to correct a genetic defect that had caused the syndrome. They then implanted the cells into lab mice and cured the unrelenting diabetes in those mice.

The findings, from researchers at Washington University School of Medicine in St. Louis, suggest the CRISPR-Cas9 technique may hold promise as a treatment for diabetes, particularly the forms caused by a single gene mutation, and it also may be useful one day in some patients with the more common forms of diabetes, such as type 1 and type 2.

The study is published online April 22 in the journal Science Translational Medicine.

Patients with Wolfram syndrome develop diabetes during childhood or adolescence and quickly require insulin-replacement therapy, requiring insulin injections multiple times each day. Most go on to develop problems with vision and balance, as well as other issues, and in many patients, the syndrome contributes to an early death.

“This is the first time CRISPR has been used to fix a patient’s diabetes-causing genetic defect and successfully reverse diabetes,” said co-senior investigator Jeffrey R. Millman, PhD, an assistant professor of medicine and of biomedical engineering at Washington University. “For this study, we used cells from a patient with Wolfram syndrome because, conceptually, we knew it would be easier to correct a defect caused by a single gene. But we see this as a stepping stone toward applying gene therapy to a broader population of patients with diabetes.”

Wolfram syndrome is caused by mutations to a single gene, providing the researchers an opportunity to determine whether combining stem cell technology with CRISPR to correct the genetic error also might correct the diabetes caused by the mutation.

A few years ago, Millman and his colleagues discovered how to convert human stem cells into pancreatic beta cells. When such cells encounter blood sugar, they secrete insulin. Recently, those same researchers developed a new technique to more efficiently convert human stem cells into beta cells that are considerably better at controlling blood sugar.

In this study, they took the additional steps of deriving these cells from patients and using the CRISPR-Cas9 gene-editing tool on those cells to correct a mutation to the gene that causes Wolfram syndrome (WFS1). Then, the researchers compared the gene-edited cells to insulin-secreting beta cells from the same batch of stem cells that had not undergone editing with CRISPR.

In the test tube and in mice with a severe form of diabetes, the newly grown beta cells that were edited with CRISPR more efficiently secreted insulin in response to glucose. Diabetes disappeared quickly in mice with the CRISPR-edited cells implanted beneath the skin, and the animals’ blood sugar levels remained in normal range for the entire six months they were monitored. Animals receiving unedited beta cells remained diabetic. Their newly implanted beta cells could produce insulin, just not enough to reverse their diabetes.

“We basically were able to use these cells to cure the problem, making normal beta cells by correcting this mutation,” said co-senior investigator Fumihiko Urano, MD, PhD, the Samuel E. Schechter Professor of Medicine and a professor of pathology and immunology. “It’s a proof of concept demonstrating that correcting gene defects that cause or contribute to diabetes — in this case, in the Wolfram syndrome gene — we can make beta cells that more effectively control blood sugar. It’s also possible that by correcting the genetic defects in these cells, we may correct other problems Wolfram syndrome patients experience, such as visual impairment and neurodegeneration.”

In the future, using CRISPR to correct certain mutations in beta cells may help patients whose diabetes is the result of multiple genetic and environmental factors, such as type 1, caused by an autoimmune process that destroys beta cells, and type 2, which is closely linked to obesity and a systemic process called insulin resistance.

“We’re excited about the fact that we were able to combine these two technologies — growing beta cells from induced pluripotent stem cells and using CRISPR to correct genetic defects,” Millman said. “In fact, we found that corrected beta cells were indistinguishable from beta cells made from the stem cells of healthy people without diabetes.”

Moving forward, the process of making beta cells from stem cells should get easier, the researchers said. For example, the scientists have developed less intrusive methods, making induced pluripotent stem cells from blood — and they are working on developing stem cells from urine samples.

“In the future,” Urano said, “we may be able to take a few milliliters of urine from a patient, make stem cells that we then can grow into beta cells, correct mutations in those cells with CRISPR, transplant them back into the patient, and cure their diabetes in our clinic. Genetic testing in patients with diabetes will guide us to identify genes that should be corrected, which will lead to a personalized regenerative gene therapy.”

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Review assesses stem cell therapy potential for treating preeclampsia — ScienceDaily

Preeclampsia is the leading cause of death and disability, for both mothers and babies, killing approximately 76,000 mothers and 500,000 babies globally every year. Despite this, the only cure at present is to deliver the placenta and the baby, with the potential for long term complications.

In recent years stem cell therapies have been investigated in animal models. A review article published in Current Hypertension Reports investigates mesenchymal stem/stromal cells (MSCs) as a potential new treatment for preeclampsia.

Senior author, Dr Lana McClements, from the University of Technology Sydney (UTS) said that preeclampsia is a pregnancy complication which manifests as a sudden onset of high blood pressure and organ damage, often involving kidneys or liver, in the second half of pregnancy.

“Most of the deaths associated with preeclampsia occur in developing or low-resource countries however preeclampsia rates in developing countries are increasing due to increase rates of obesity, diabetes and age of women getting pregnant. While there are fewer deaths caused by preeclampsia in developing countries, the economic burden on the healthcare systems is significant,” she says.

“In addition, studies show that beyond life-threatening complications in pregnancy preeclampsia is associated with increased maternal and offspring ill health in later life which makes this review important. If stem cell therapies have potential to treat this condition in pregnancy then their application needs to be assessed for clinical trials,” she says.

Dr McClements and her co-authors from the Mayo Clinic (USA); University of Belgrade (Serbia); University of Nis (Serbia), Queen’s University Belfast (UK) and Serbian Academy of Sciences and Arts, reviewed the therapeutic potential and mechanisms of MSCs in the context of preeclampsia.

MSCs are the most widely used stem cells for treatment of many diseases including cardiovascular disease. More recently, a limited number of studies (five) have tested these stem cells, or their associated secreted cargo (vesicles) as novel treatment options for preeclampsia in pre-clinical (animal) models showing promising results.

The authors say that of particular interest to low-resourced countries are vesicles secreted from these stem cells due to their stability and avoiding the need for expensive GMP cell manufacturing facilities.

“Preeclampsia develops due to a complex set of conditions. Our review shows that there is potential to use stem cells as therapy but we still don’t understand the mechanism by which MSCs might repair damage in the condition.

“Further work is needed to maximize their therapeutic potential and minimise possible side effects before they can be introduced in a clinical setting, this is why we are pursuing this important research in my laboratory at UTS to help treat such a devastating disease,” Dr McClements says.

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Researchers repurpose classic chemotherapy drug to overcome cancer therapy resistance — ScienceDaily

Drug resistance is a major obstacle in cancer treatment — leading to relapse for many patients. In a new study, published online April 20, 2020, in Nature Cell Biology, researchers from the Stowers Institute for Medical Research, Children’s Mercy Kansas City, and The University of Kansas Cancer Center report on a promising new strategy to overcome drug resistance in leukemia, using targeted doses of the widely-used chemotherapy drug doxorubicin.

The study’s researchers found that low doses of the anthracycline antibiotic doxorubicin inhibit the interaction between two molecular pathways that work closely together to promote tumor growth and resistance to therapy. The targeted approach also clears the way for cancer-targeting immune cells to do their work, an unexpected and novel finding, according to the study authors.

“In low doses, doxorubicin actually stimulated the immune system, in contrast with the typical clinical doses, which were immunosuppressive, killing healthy immune cells indiscriminately,” says John M. Perry, PhD, a researcher with the Children’s Mercy Research Institute at Children’s Mercy. He completed his postdoctoral work at Stowers and is first author of the report.

The findings are the result of a decade-spanning collaborative effort among researchers at the Stowers Institute, Children’s Mercy, The University of Kansas Cancer Center and other institutions, evolving from their studies on how normal, healthy stem cells self-renew.

Early in their studies, Stowers Institute Investigator Linheng Li, PhD, and Research Specialist Xi He, MD, showed that the protein kinase Akt could enhance Wnt signaling via phosphorylating beta-catenin, thus promoting tumorigenesis in the gut. Perry further investigated the Wnt/beta-catenin and PI3K/Akt pathways in the hematopoietic (blood-forming) system. Using a mouse model with genetic modifications of the Wnt/beta-catenin and PI3K/Akt pathways, Perry found that the two pathways cooperate to drive stem cell renewal, thus resulting in excessive blood-forming stem cell production. But instead of just expanding the stem cells, the permanent activation of the pathways caused the mice also to develop leukemia. Intrigued, the researchers shifted their focus to inhibiting interaction between those same pathways to target leukemia stem cells.

Many drugs that directly target the Wnt/beta-catenin or PI3K/Akt pathways eventually fail because cancer cells evolve resistance to them, and broadly-acting chemotherapeutic drugs can have harsh side effects and systemic toxicity. The researchers collaborated with Scott Weir, PhD, and Anuradha Roy, PhD, at The University of Kansas (KU) Cancer Center, to search for an alternative among the compounds cataloged in the center’s small molecule library.

“Our idea was to find a drug with the goal of blocking the interaction between Wnt/beta-catenin and PI3K/Akt and reduce the toxicity,” says Li, who serves as liaison between Stowers and the KU Cancer Center and co-leads the center’s cancer biology research program.

The team conducted high-throughput drug screening, which showed that doxorubicin did the best job of inhibiting the interaction between the two pathways. They found that the drug’s inhibitory powers worked at low doses, which offers an advantage over administering it at high doses as a chemotherapeutic drug where it can cause lasting heart damage in some patients.

Samples collected from pediatric leukemia patients at Children’s Mercy were also central to the study. A diagnostic sample was collected from each patient before and after chemotherapy treatment to compare therapy-resistant leukemia stem cells to therapy-sensitive leukemia stem cells. Then the samples were transplanted into mice to test whether they developed leukemia and whether low-dose doxorubicin treatment improved their survival and reduced leukemia development.

“We found that mice receiving patient sample transplants with therapy-resistant leukemia stem cells rapidly developed leukemia, but low-dose doxorubicin treatment improved survival by reducing leukemia stem cells,” Perry says. “However, mice receiving patient sample transplants that did not contain therapy-resistant leukemia stem cells did not respond to low-dose doxorubicin treatment. These results showed that chemoresistant leukemia stem cells from patients could be functionally reduced with low-dose doxorubicin treatment, at least in an in vivo animal model assay.”

After successful testing in mouse models, the researchers worked with Tara Lin, MD, at the KU Cancer Center to conduct a small-scale clinical trial to test low-dose anthracycline treatment on adults with treatment-resistant acute myeloid leukemia (AML). The trial used daunorubicin, a chemotherapy drug in the same class as doxorubicin, which is widely used in treating AML. Bone marrow was collected immediately prior to treatment and again post-treatment. Half of the study participants responded to the treatment and had reduced numbers of leukemia stem cells exhibiting the Akt-activated beta-catenin biomarker.

In addition to these encouraging results, the overarching study also revealed surprising insights into immune escape — a hallmark of cancer development in which cancerous cells evade the immune system and proliferate. Mechanistically, they found that leukemia stem cells express multiple proteins known as immune checkpoints, which turn off immune responses that might otherwise recognize and eliminate leukemia stem cells. Another team member, Fang Tao, PhD, uncovered that beta-catenin binds to multiple immune checkpoint gene loci. Low-dose doxorubicin treatment reduced expression of these immune checkpoints, including PD-L1, TIM3, and CD24, which exposed otherwise resistant leukemia stem cells to immune-mediated cell killing.

Going forward, at Children’s Mercy, Perry is conducting further research to understand ways to screen other drugs that synergize with low-dose doxorubicin to kill resistant cells while reactivating anticancer immunity in pediatric patients. His team has recently launched a clinical trial on low-dose doxorubicin in pediatric patients. At Stowers, the Li Lab is investigating similar strategies for overcoming cancer therapy resistance in solid tumor cancers including breast cancer, glioblastoma, and colon cancer.

“The research holds promise as a more effective strategy to overcome cancer therapy resistance and immune escape that can be used in combination with other cancer therapies including chemotherapy, radiation, and immunotherapy for patients with leukemia and other types of cancer,” Li says.

Low-dose doxorubicin also avoids the harsh side effects of high-dose doxorubicin, potentially offering patients a better quality of life. In high doses, doxorubicin damages the heart muscle. Even when patients survive long-term, highly toxic anticancer treatments often cause long-term health problems and reduced life expectancy.

“Pediatric patients should live another half-century or more, so we need to do a better job of ensuring not only long-term survival, but healthy and productive lives,” Perry says.

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Stem cells in human embryos commit to specialization surprisingly early — ScienceDaily

The point when human embryonic stem cells irreversibly commit to becoming specialised has been identified by researchers at the Francis Crick Institute.

Our biological history can be traced back to a small group of cells called embryonic stem cells, which through cell division, give rise to cells that specialise to perform a specific role in the body — a process known as differentiation.

Understanding when and how embryonic stem cells specialise provides insights into healthy differentiation and how cells ‘remember’ what type of cell they are. This process can go wrong in cancer, when cells ‘forget’ their identity and change into the wrong type.

As part of the research, published in Cell Stem Cell, Crick scientists found that embryonic stem cells differentiate unexpectedly early, irreversibly committing to become each of the more than 200 cell types in the body.

They showed this was as a result of a newly identified small group of genes becoming activated, which they named ‘early-commitment genes’.

“Working with stem cells and mathematical models, we’ve identified a new class of genes which are responsible for regulating one of the earliest stages of human development,” says Silvia Santos, author and group leader in the Quantitative Cell Biology Laboratory at the Crick.

“Once these genes are activated, it’s a question of minutes before the cells fully commit to differentiation. The speed of this is incredibly surprising, especially if you consider how the first signs of differentiation, that’s the embryo developing the first embryonic germ layers, take about three days. These layers ultimately give rise to all the tissues in the growing fetus weeks later.”

The researchers focused on one early-commitment gene, called GATA3. When this gene was activated experimentally in the lab, embryonic stem cells quickly committed to differentiation. On the other hand, when this gene was deleted, this process was sluggish and not quite right.

“GATA3 is crucial to the healthy, timely differentiation of stem cells. Once it’s switched on, this gene triggers a positive feedback loop, which helps it stay active. In turn, this ensures that the cells remain differentiated, and do not reverse back to a stem cell state,” says Alexandra Gunne-Braden, co-lead author and postdoc in the Quantitative Cell Biology Laboratory at the Crick.

This research used stem cells taken from embryos donated by people undergoing IVF. The donated embryos were not needed in the course of their fertility treatment and would have otherwise been destroyed.

“When embryonic stem cells commit to specialisation is a fundamental and yet until now, unanswered question,” continues Silvia Santos.

“It’s important we understand more about this, as the healthy function of cells is underpinned by the process of how cells acquire and remember their identity during the process of differentiation. This valuable insight into early human development could open up new avenues for research into diseases that occur when this process goes wrong.”

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Early detection of Crohn’s disease flare-ups leads to improved therapy options — ScienceDaily

Intestinal stem cell metabolism is facilitated by mitochondria — the in-cell power plants. Chronic inflammation processes inhibit the cells’ metabolism and lead to functional loss of these stem cells.

In collaboration with the Helmholz Zentrum München and the Université de Paris, a TUM research team has discovered this connection by analyzing intestinal epithelial cells of Crohn’s disease patients and comparing them to mouse model findings.

The interrelated role of stem cells and Paneth cells

Stem cells are indispensable for the maintenance and regeneration of tissues. Intestinal stem cells inside the intestines are intermingled with so-called Paneth cells, which are responsible for the local immune defense and for creating an environment in which the stem cells can prosper, thus termed guardians of the stem cell niche.

Patients suffering from Crohn’s disease have fewer Paneth cells and furthermore, these are limited in their functionality. The research group examined the causes for alterations in Paneth cells and attempted to determine the importance of stem cell metabolism in this context.

In addition to mouse studies, the researchers analyzed intestinal biopsies from Crohn’s disease patients, characterizing the stem cell niche meticulously. After six months, the patients’ intestines were examined again endoscopically focusing on finding signs of inflammation.

Predicting Crohn’s disease recurrence by observing the appearance of stem cells

The study showed that microscopic alterations in stem cell niche were particularly prevalent in those patients who showed symptoms of a relapse of inflammation after six months.

“These changes in the stem cell niche are a very early indicator for the start of inflammatory processes. Therefore, the appearance of the stem cell niche can be used to evaluate the probability of a disease recurrence after the resection of originally affected parts of the small intestine. This presents a reasonable starting point for therapeutic intervention,” explained Dirk Haller, Professor for Nutrition and Immunology at TUM.

Restoring stem cell function

In both human patients and mouse models, alterations in Paneth and stem cells coincided with decreased mitochondria functionality.

Knowing that a lowered mitochondrial respiration leads to alterations in the stem cell niche, the researchers used dichloracetate (DCA), a substance applied in cancer therapy leading to an increase in mitochondrial respiration.

The shift in cellular metabolism induced by DCA was able to restore the intestinal stem cell functionality of mice suffering from inflammation, as demonstrated in intestinal organoids, organ-like structures cultured ex vivo.

Therapeutic approach for prolonging the inflammation-free phases of Crohn’s disease

“These findings point to a new therapeutic approach for prolonging the inflammation-free remission phases of Crohn’s disease,” said Eva Rath, scientist at the TUM School of Life Sciences Weihenstephan and co-author of the study.

The aim of further research is to investigate the effect of DCA in animal models and patients in more detail. A so-called metabolic intervention — making targeted changes in the cells’ metabolism — could prevent functional loss of stem cells and Paneth cells, which both maintain the intestinal barrier. This could lead to preventing subsequent inflammation.

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New path to modeling eye disease, advancing therapies — ScienceDaily

Researchers have discovered a technique for directly reprogramming skin cells into light-sensing rod photoreceptors used for vision. The lab-made rods enabled blind mice to detect light after the cells were transplanted into the animals’ eyes. The work, funded by the National Eye Institute (NEI), published April 15 in Nature. The NEI is part of the National Institutes of Health.

Up until now, researchers have replaced dying photoreceptors in animal models by creating stem cells from skin or blood cells, programming those stem cells to become photoreceptors, which are then transplanted into the back of the eye. In the new study, scientists show that it is possible to skip the stem-cell intermediary step and directly reprogram skins cells into photoreceptors for transplantation into the retina.

“This is the first study to show that direct, chemical reprogramming can produce retinal-like cells, which gives us a new and faster strategy for developing therapies for age-related macular degeneration and other retinal disorders caused by the loss of photoreceptors,” said Anand Swaroop, Ph.D., senior investigator in the NEI Neurobiology, Neurodegeneration, and Repair Laboratory, which characterized the reprogrammed rod photoreceptor cells by gene expression analysis.

“Of immediate benefit will be the ability to quickly develop disease models so we can study mechanisms of disease. The new strategy will also help us design better cell replacement approaches,” he said.

Scientists have studied induced pluripotent stem (iPS) cells with intense interest over the past decade. IPSCs are developed in a lab from adult cells — rather than fetal tissue — and can be used to make nearly any type of replacement cell or tissue. But iPS cell reprogramming protocols can take six months before cells or tissues are ready for transplantation. By contrast, the direct reprogramming described in the current study coaxed skin cells into functional photoreceptors ready for transplantation in only 10 days. The researchers demonstrated their technique in mouse eyes, using both mouse- and human-derived skin cells.

“Our technique goes directly from skin cell to photoreceptor without the need for stem cells in between,” said the study’s lead investigator, Sai Chavala, M.D., CEO and president of CIRC Therapeutics and the Center for Retina Innovation. Chavala is also director of retina services at KE Eye Centers of Texas and a professor of surgery at Texas Christian University and University of North Texas Health Science Center (UNTHSC) School of Medicine, Fort Worth.

Direct reprogramming involves bathing the skin cells in a cocktail of five small molecule compounds that together chemically mediate the molecular pathways relevant for rod photoreceptor cell fate. The result are rod photoreceptors that mimic native rods in appearance and function.

The researchers performed gene expression profiling, which showed that the genes expressed by the new cells were similar to those expressed by real rod photoreceptors. At the same time, genes relevant to skin cell function had been downregulated.

The researchers transplanted the cells into mice with retinal degeneration and then tested their pupillary reflexes, which is a measure of photoreceptor function after transplantation. Under low-light conditions, constriction of the pupil is dependent on rod photoreceptor function. Within a month of transplantation, six of 14 (43%) animals showed robust pupil constriction under low light compared to none of the untreated controls.

Moreover, treated mice with pupil constriction were significantly more likely to seek out and spend time in dark spaces compared with treated mice with no pupil response and untreated controls. Preference for dark spaces is a behavior that requires vision and reflects the mouse’s natural tendency to seek out safe, dark locations as opposed to light ones.

“Even mice with severely advanced retinal degeneration, with little chance of having living photoreceptors remaining, responded to transplantation. Such findings suggest that the observed improvements were due to the lab-made photoreceptors rather than to an ancillary effect that supported the health of the host’s existing photoreceptors,” said the study’s first author Biraj Mahato, Ph.D., research scientist, UNTHSC.

Three months after transplantation, immunofluorescence studies confirmed the survival of the lab-made photoreceptors, as well as their synaptic connections to neurons in the inner retina.

Further research is needed to optimize the protocol to increase the number of functional transplanted photoreceptors.

“Importantly, the researchers worked out how this direct reprogramming is mediated at the cellular level. These insights will help researchers apply the technique not only to the retina, but to many other cell types,” Swaroop said.

“If efficiency of this direct conversion can be improved, this may significantly reduce the time it takes to develop a potential cell therapy product or disease model,” said Kapil Bharti, Ph.D., senior investigator and head of the Ocular and Stem Cell Translational Research Section at NEI.

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Single cell cloning tells the story of abnormal cells — ScienceDaily

Two stem cell experts have found an abundance of abnormal stem cells in the lungs of patients who suffer from Chronic Obstructive Pulmonary Disease (COPD), a leading cause of death worldwide. Frank McKeon, professor of biology and biochemistry and director of the Stem Cell Center, and Wa Xian, research associate professor at the center, used single cell cloning of lung stem cells to make their discovery. Now they are targeting the cells for new therapeutics.

“We actually found that three variant cells in all COPD patients drive all the key features of the disease. One produces tremendous amounts of mucins which block the small airways, while the other two drive fibrosis and inflammation which together degrade the function of the lung,” Xian reports in the May 14 issue of the journal Cell. “These patients have normal stem cells, though not many of them, but they are dominated by the three variant cells that together make up the disease,” she said.

COPD is a progressive inflammatory disease of the lungs marked by chronic bronchitis, small airway occlusion, inflammation, fibrosis and destruction of alveoli, tiny air sacs in the lungs which exchange oxygen and carbon dioxide molecules in the blood. The Global Burden of Disease Study reports 251 million cases of COPD globally in 2016.

“It’s a frustrating disease to care for. We can try and improve the symptoms, but we don’t have anything that can cure the disease or prevent death,” said UConn Health pulmonologist and critical care doctor Mark Metersky, who gathered the stem cells from lung fluid while performing bronchoscopies.

Despite its accounting for more deaths than any single disease on the planet, relatively little has been written or understood about the root cause of COPD.

Over the past decade, Xian and McKeon developed technology for cloning stem cells of the lungs and airways and have been at it since, noting that different parts of the airways give different stem cells, related but distinguishable.

“It’s quite remarkable,” said McKeon. “In the deep lung, the distal airway stem cells gave rise to both the distal tubes and the alveoli and our research indicates those are the stem cells that make it possible for lungs to regenerate on their own.” Xian and McKeon discovered lung regeneration in 2011 in their studies of subjects recovering from infections by an H1N1 influenza virus that was nearly identical to that which sparked the 1918 pandemic.

Xian and McKeon found that, in contrast to normal lungs, COPD lungs were inundated by three unusual variant lung stem cells that are committed to form metaplastic lesions known to inhabit COPD lungs, but seen by many as a secondary effect without a causal link to the pathology of COPD. After the team’s postdoctoral fellow, Wei Rao, transplanted each of the COPD clones into immunodeficient subjects, the team found they not only gave rise to the distinct metaplastic lesions of COPD, but they separately triggered the triad of pathologies of COPD including mucus hypersecretion, fibrosis and chronic inflammation.

“The long-overlooked metaplastic lesions in COPD were, in fact, driving the disease rather than merely secondary consequences of the condition,” said McKeon.

Now that the team knows the identity of the cells that cause inflammation, fibrosis and small airway obstruction, they are hard at work screening them against libraries of drug-like molecules to discover new therapeutics.

“As we now know the specific cells responsible for COPD pathology, we can target them, much as we would cancer, with specific drugs that selectively kill them off and leave the normal cells to regenerate normal lung tissue,” said Xian.

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Experimental drug offers hope for preventing cancer relapse — ScienceDaily

A drug that is well-tolerated in patients and prevents cancer coming back in mice has been identified by researchers at the Francis Crick Institute.

One of the biggest challenges in cancer research is preventing cancer returning in patients who have already had treatment. A reason for these relapses is that some cancer cells survive and are able to grow into a new tumour.

As part of the study published in Nature Communications, researchers showed that an experimental drug, Quisinostat, could stop tumour re-growth after initial treatment in live mice, and prevent expansion of surviving human cancer cells in culture.

The drug works by increasing the amount of a protein called histone H1.0 within the tumour cells. This protein stops the cancer cells from replicating and so the tumour from growing.

When the team tested the drug on tumours in mice, it halted tumour growth. And, when it was tested on cells taken from patients with breast, lung or pancreatic cancer, the cancerous cells were trapped in a non-dividing state.

The researchers hope that if proven to be effective in further tests and clinical trials, this drug could be given to patients after treatment to prevent any cancerous cells left behind from driving disease relapse. Importantly, the effect of Quisinostat does not depend on how cancer cells survived treatment, something that varies from patient to patient, and across cancer types, and could have a potentially broad therapeutic benefit.

Cristina Morales Torres, lead author and Principal Laboratory Research Scientist in the Cancer Epigenetics Laboratory at the Crick, says: “This drug works by disabling the cells that fuel long-term cancer growth and drive disease relapse. These early findings even suggest it may be more effective than commonly used drugs that inhibit tumour growth.

“Further research is still needed to confirm whether this drug could prevent cancer coming back in people or if it could be used to control someone’s disease long term.”

Importantly, this early work also suggests that Quisionostat could impact cancerous cells while leaving healthy cells unharmed.

Paola Scaffidi, co-author and Group Leader of the Cancer Epigenetics Laboratory at the Crick and Professorial Research Associate at the UCL Cancer Institute, says: “Just like stem cells that continuously produce progeny to keep our normal tissues healthy, cancer cells grow, divide and use energy. That’s why finding a potential drug that halts tumour growth without hurting normal cells has been a challenge. Excitingly, with Quisinostat, we’ve seen no harm to healthy stem cells in our initial studies.”

The next step for these researchers will be to understand why Quisinostat has a different effect on healthy and malignant cells and whether histone H1.0 can tell us what makes a cancer cell distinct from a stem cell.

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Even before cancer is detectable, glow-in-the-dark cells show mutations driving malignancy — ScienceDaily

Duke Cancer Institute researchers have observed how stem cell mutations quietly arise and spread throughout a widening field of the colon until they eventually predominate and become a malignancy.

Using an innovative modeling system in mice, the researchers visually tagged colon cancer mutations by causing stem cells to glow. Mutations found in colon cancer were then visualized in the animals, illuminating a sort of tournament-to-the-death underway in the intestine in which one or another mutation prevailed over the others to become the driving force of a malignancy.

“This study provides new insight into the previously invisible process in which mutant precancerous stem cells spread throughout the colon and seed cancer,” said Joshua Snyder, Ph.D., assistant professor in the departments of Surgery and Cell Biology at Duke and corresponding and co-senior author of a study publishing online Dec. 2 in the journal Nature Communications.

“Our technique sets a firm foundation for testing new therapies that interrupt this early, pre-malignant process. We hope to one day target and eliminate these stealth precancerous cells to prevent cancer,” Snyder said.

Snyder and colleagues — including co-senior author H. Kim Lyerly, M.D., George Barth Geller Professor at Duke ¬ — applied the molecular dyeing technique in a new way, tagging several common colon cancer mutations in the stem cells of a single tumor to create a fluorescent barcode.

When transferred to a mouse, the rainbow of fluorescent stem cells could be visually tracked, revealing the cellular and molecular dynamics of pre-cancerous events.

In this way, the researchers found key differences in how the intestinal habitats common to babies and adults grow pre-cancerous fields of mutant cells. At a critical period, newborns are sensitive to the effects of mutations within intestinal stem cells. This insidiously seeds large fields of premalignant mutated cells throughout the intestine — a process called field cancerization — that dramatically increases cancer risk. These fields of mutated cells can grow and spread for years without being detected by current screening technologies; often, they remain harmless, but under proper conditions, can rapidly become cancerous later in adults.

The researchers also observed that some colon cancer mutations found in patients can lead to a striking increase in the fertility of the environment surrounding precancerous fields. Ultimately, this leads to the rapid spread of fields throughout the intestine, with lethal consequences.

Certain common mutations that arise from external sources, such as an injury or an environmental exposure, could also disrupt the environment surrounding the stem cell and lead to the rapid growth and spread of precancerous fields. These occurrences can be especially lethal in adults and occur much more rapidly than previously expected — as if dropping a match on a drought-stricken forest.

“Field cancerization has been suggested to be the defining event that initiates the process of cancer growth, including cancers of the breast, skin and lung,” Snyder said. “Our technique allows us to model how premalignant cells compete and expand within a field by simple fluorescent imaging, potentially leading to earlier diagnosis and treatment.”

Snyder said additional studies are underway using the fluorescent barcoding to view the cancer fields in breast cancer, aiming to learn more about when a pre-cancerous condition known as ductal carcinoma in situ is driven by malignant vs. benign mutations.

In addition to Snyder and Lyerly, study authors include Peter G. Boone, Lauren K. Rochelle, Veronica Lubkov, Wendy L. Roberts, P.J. Nicholls, Cheryl Bock, Mei Lang Flowers, Richard J. von Furstenberg, Joshua D. Ginzel, Barry R. Stripp, Pankaj Agarwal, Alexander D. Borowsky, Robert D. Cardiff, Larry S. Barak and Marc G. Caron.

The work was supported by the National Cancer Institute (512-CA100639-10, 1K22CA212058, R21CA173245, 1R33CA191198, NICHD 5T32HD040372), Sage Biosciences (3U24CA209923-01S1), the Department of Defense (W81XWH-12-1-0447) and Duke Surgery.

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