Stem Cells May Be The Key To Staying Strong In Old Age

University of Rochester Medical Center researchers have discovered that loss of muscle stem cells is the main driving force behind muscle decline in old age in mice. Their finding challenges the current prevailing theory that age-related muscle decline is primarily caused by loss of motor neurons. Study authors hope to develop a drug or therapy that can slow muscle stem cell loss and muscle decline in the future.

As early as your mid 30’s, the size and strength of your muscles begins to decline. The changes are subtle to start — activities that once came easily are not so easy now — but by your 70’s or 80’s, this decline can leave you frail and reliant on others even for simple daily tasks. While the speed of decline varies from person to person and may be slowed by diet and exercise, virtually no one completely escapes the decline.

“Even an elite trained athlete, who has high absolute muscle strength will still experience a decline with age,” said study author Joe Chakkalakal, Ph.D., assistant professor of Orthopaedics in the Center for Musculoskeletal Research at URMC.

Chakkalakal has been investigating exactly how muscle loss occurs in aging mice in order to figure out how humans might avoid it.

In a study, published today in eLife, Chakkalakal and lead author Wenxuan Liu, Ph.D., recent graduate of the Biomedical Genetics Department at URMC, define a new role for stem cells in the life long maintenance of muscle. All adults have a pool of stem cells that reside in muscle tissue that respond to exercise or injury — pumping out new muscle cells to repair or grow your muscles. While it was already known that muscle stem cells die off as you age, Chakkalakal’s study is the first to suggest that this is the main driving factor behind muscle loss.

To better understand the role of stem cells in age-related muscle decline, Chakkalakal and his team depleted muscle stem cells in mice without disrupting motor neurons, nerve cells that control muscle. The loss of stem cells sped up muscle decline in the mice, starting in middle, rather than old age. Mice that were genetically altered to prevent muscle stem cell loss maintained healthier muscles at older ages than age-matched control mice.

At the same time, Chakkalakal and his team did not find evidence to support motor neuron loss in aging mice. Very few muscle fibers had completely lost connection with their corresponding motor neurons, which questions the long-held and popular “Denervation/Re-innervation” theory. According to the theory, age-related muscle decline is primarily driven by motor neurons dying or losing connection with the muscle, which then causes the muscle cells to atrophy and die.

“I think we’ve shown a formal demonstration that even for aging sedentary individuals, your stem cells are doing something,” said Chakkalakal. “They do play a role in the normal maintenance of your muscle throughout life.”

Chakkalakal is building on this discovery and searching for a drug target that will allow him to maintain the muscle stem cell pool and stave off muscle degeneration as long as possible and he hopes this discovery will help move the field forward.

Stem Cell Trial for Stroke Patients Suffering Chronic Motor Deficits Begins at UTHealth

A clinical trial to evaluate the safety and efficacy of a stem cell product injected directly into the brain to treat chronic motor deficits from ischemic stroke has begun at McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth).

McGovern Medical School at UTHealth is the only site in Texas and the central south portion of the country to open enrollment for the multi-institutional, phase 2B study – the first in the U.S. for chronic stroke. Surgeries will be conducted at Memorial Hermann-Texas Medical Center.

“This trial is one of the first randomized, sham-controlled studies to test the efficacy of administering adult-derived stem cells in patients disabled with a chronic stroke,” said Sean I. Savitz, M.D., professor and the Frank M. Yatsu Chair in Neurology at McGovern Medical School and director of the UTHealth Institute for Stroke and Cerebrovascular Disease. “We were chosen as one of only a handful of referral centers in the nation and patients from all over the country will be referred to our center for this trial. Overall, the study adds to our growing regenerative medicine program for patients with neurological disorders.”

In the double-blind, sham-surgery controlled study, patients randomized to the study intervention will receive a stem cell product made by SanBio and patients must have chronic motor deficits from an ischemic stroke to be eligible for the study. The product, administered through tiny holes bored into the skull and placed near the site of the damage, came from the bone marrow of two healthy adult donors. Enrollment is limited to patients who are between six and 60 months post-stroke and have a chronic motor neurological deficit.

Results of a phase 1/2A study of the stem cell product, presented at the International Society of Stem Cell Research Meeting and published in the journal, Stroke, showed statistically significant improvements in motor function and no safety concerns.

The UTHealth Stroke Program at McGovern Medical School, led by Savitz, is one of the most active research and clinical programs in the country. It was one of the lead sites in the National Institute of Neurological Disease and Stroke’s (NINDS) tPA stroke study; was one of eight centers in the country funded by the NIH to conduct specialized translational research to develop novel acute stroke therapies; and receives NINDS fellowship funding to train the next generation of academic leaders in cerebrovascular disease.

UW Scientists Find Key Cues to Regulate Bone-Building Cells

The prospect of regenerating bone lost to cancer or trauma is a step closer to the clinic as University of Wisconsin-Madison scientists have identified two proteins found in bone marrow as key regulators of the master cells responsible for making new bone.

In a study published online today (Feb. 2, 2017) in the journal Stem Cell Reports, a team of UW-Madison scientists reports that the proteins govern the activity of mesenchymal stem cells — precursor cells found in marrow that make bone and cartilage. The discovery opens the door to devising implants seeded with cells that can replace bone tissue lost to disease or injury.

“These are pretty interesting molecules,” explains Wan-Ju Li, a UW-Madison professor of orthopedics and biomedical engineering, of the bone marrow proteins lipocalin-2 and prolactin. “We found that they are critical in regulating the fate of mesenchymal stem cells.”

Li and Tsung-Lin Tsai, a UW-Madison postdoctoral researcher, scoured donated human bone marrow using high-throughput protein arrays to identify proteins of interest and then determined the activity of mesenchymal stem cells exposed to the proteins in culture. A goal of the study, says Li, is to better understand the bone marrow niche where mesenchymal stem cells reside in the body so that researchers can improve culture conditions for growing the cells in the lab and for therapy.

The Wisconsin researchers found that exposing mesenchymal stem cells to a combination of lipocalin-2 and prolactin in culture reduces and slows senescence, the natural process that robs cells of their power to divide and grow. Li says keeping the cells happy and primed outside the body, but reining in their power to grow and make bone tissue until after they are implanted in a patient, is key.

The ability to precisely manipulate mesenchymal stem cells in the laboratory dish and keep them poised to divide and form bone on cue helps pave the way for using cell-bearing three-dimensional matrices to reconstruct large swaths of bone lost to tumors or major trauma. Because bone has some natural healing properties, things like breaks and fractures can often mend themselves. But when large pieces of bone are lost, clinical intervention is required.

“We’re seeking better treatments for bone repair,” says Li, who is affiliated with the UW School of Medicine and Public Health.

To engineer the growth of new bone in the body through regenerative medicine first requires generating large amounts of good quality cells in the lab, notes Li. In the body stem cells are rare. But if cell growth, differentiation and quality can be controlled in the lab dish, it may be possible to create stocks of cells for therapeutic applications and prime them for bone regeneration once implanted in a patient.

The Wisconsin team successfully tested human cells treated with lipocalin-2 and prolactin to regrow bone by implanting them in mice with a calvarial defect, where part of the skullcap has been surgically removed to model critical-sized bone loss.

The human marrow used in the new Wisconsin study was donated by patients undergoing hip replacement surgery. Thus, a caveat to the study is that the protein factors identified by Li and his colleague came from donors with osteoarthritis. However, Li expressed confidence that the factors from the marrow used in the study would be similar or identical to what occurs in a healthy patient.

New stem cell delivery approach regenerates dental pulp-like tissue in a rodent model

When a tooth is damaged, either by severe decay or trauma, the living tissues that comprise the sensitive inner dental pulp become exposed and vulnerable to harmful bacteria. Once infection takes hold, few treatment options–primarily root canals or tooth extraction–are available to alleviate the painful symptoms.

Researchers at Tufts University School of Dental Medicine (TUSDM) now show that using a collagen-based biomaterial to deliver stem cells inside damaged teeth can regenerate dental pulp-like tissues in animal model experiments. The study, published online in the Journal of Dental Research on Dec. 15, supports the potential of this approach as part of a strategy for restoring natural tooth functionality.

“Endodontic treatment, such as a root canal, essentially kills a once living tooth. It dries out over time, becomes brittle and can crack, and eventually might have to be replaced with a prosthesis,” said senior study author Pamela Yelick, PhD, professor at TUSDM and director of its Division of Craniofacial and Molecular Genetics. “Our findings validate the potential of an alternative approach to endodontic treatment, with the goal of regenerating a damaged tooth so that it remains living and functions like any other normal tooth.”

Yelick and her colleagues, including lead study author Arwa Khayat, former graduate student in dental research at TUSDM, examined the safety and efficacy of gelatin methacrylate (GelMA)–a low-cost hydrogel derived from naturally occurring collagen–as a scaffold to support the growth of new dental pulp tissue. Using GelMA, the team encapsulated a mix of human dental pulp stem cells–obtained from extracted wisdom teeth–and endothelial cells, which accelerate cell growth. This mix was delivered into isolated, previously damaged human tooth roots, which were extracted from patients as part of unrelated clinical treatment and sterilized of remaining living tissue. The roots were then implanted and allowed to grow in a rodent animal model for up to eight weeks.

The researchers observed pulp-like tissue inside the once empty tooth roots after two weeks. Increased cell growth and the formation of blood vessels occurred after four weeks. At the eight-week mark, pulp-like tissue filled the entire dental pulp space, complete with highly organized blood vessels populated with red blood cells. The team also observed the formation of cellular extensions and strong adhesion into dentin–the hard, bony tissue that forms the bulk of a tooth. The team saw no inflammation at the site of implantation, and found no inflammatory cells inside implanted tooth roots, which verified the biocompatibility of GelMA.

Control experiments, which involved empty tooth roots or tooth roots with only GelMA and no encapsulated cells, showed significantly less growth, unorganized blood vessel formation, and poor or nonexistent dentin attachment.

The results support GelMA-encapsulated human dental stem cells and umbilical vein endothelial cells as part of a promising strategy to restore normal tooth function, according to the study authors. However, they note that the current study was limited to partial tooth roots and did not examine nerve formation in regenerated dental pulp tissue. They emphasize the need for additional safety and efficacy studies in larger animal models before human clinical trials can be considered.

“A significant amount of work remains to be done, but if we can extend and validate our findings in additional experimental models, this approach could become a clinically relevant therapy in the future,” said Yelick, who is also a member of the Cell, Molecular & Developmental Biology; Genetics; and Pharmacology & Experimental Therapeutics programs at the Sackler School of Graduate Biomedical Sciences at Tufts. “Our work is early stage, but we are excited for the possibility of someday giving patients the option of regenerating their own teeth.” Continue reading “New stem cell delivery approach regenerates dental pulp-like tissue in a rodent model”

Leading Cell Therapy Company Pluristem to Partner with Japan’s Sosei for Commercialization of Regenerative Medicines in Japan

In a major global regenerative medicine deal, Israel-based Pluristem Therapeutics and Japan’s Sosei CVC, the venture capital arm of Japanese biopharma company Sosei Group, agreed to form a joint venture (JV) to commercialize Pluristem’s PLX-PAD cells in Japan. The deal marks Pluristem’s commercial entry into Japan and expands Sosei’s pipeline into regenerative medicines.

Pluristem has been active in the Japan market through discussions with, and applications to, Japan’s health regulatory agency, Pharmaceuticals and Medical Devices Agency (PMDA), seeking accelerated approval pathways for its PLX-PAD cells. The successful result is the PDMA’s acceptance of PLX-PAD cells into the accelerated pathways for regenerative medicine, making possible regulatory approval of PLX-PAD cells in the treatment of Critical Limb Ischemia (CLI) following just one 75-person clinical trial. This JV deal in Japan confirms Pluristem’s strategy of pursuing early approval pathways, as they also achieved in Europe.

Per the terms of the agreement between the two companies, an $11 million investment will be made by Sosei into the JV to fund a clinical trial of PLX-PAD for CLI that may directly lead to early conditional marketing approval and reimbursement based the PMDA’s accelerated regulatory pathway for regenerative medicine.  Pluristem gets 35% of the JV and its future profits. All proprietary rights related to PLX-PAD will be exclusively owned by Pluristem.

Sosei was likely compelled to partner with Pluristem based on the company’s advanced stem cell technology and its regulatory advantages in Japan. In addition to this JV with Pluristem, Sosei has partnerships with Novartis, AstraZeneca, MedIumme, and others. Pluristem and Sosei plan to enter into a definitive agreement no later than March 31, 2017.

Stem Cell-Based Test Predicts Leukemia Patients’ Response to Therapy to Help Tailor Treatment

Newswise — (TORONTO, Canada – Dec. 7, 2016) – Leukemia researchers at Princess Margaret Cancer Centre have developed a 17-gene signature derived from leukemia stem cells that can predict at diagnosis if patients with acute myeloid leukemia (AML) will respond to standard treatment.

The findings, published online today in Nature, could potentially transform patient care in AML by giving clinicians a risk scoring tool that within a day or two of diagnosis can predict individual response and help guide treatment decisions, says co-principal investigator Dr. Jean Wang, Affiliate Scientist at the Princess Margaret, University Health Network (UHN). Dr. Wang is also an Assistant Professor, Faculty of Medicine, University of Toronto and a Hematologist at Toronto General Hospital, UHN. She talks about the research at https://youtu.be/ilSiyUP9HE0.

The new biomarker is named the LSC17 score as it comes from the leukemia stem cells that drive disease and relapse. These dormant stem cells have properties that allow them to resist standard chemotherapy, which is designed to defeat rapidly dividing cancer cells. The persistence of these stem cells is the reason the cancer comes back in patients despite being in remission following treatment. AML is one of the most deadly types of leukemia and the most common type of acute leukemia in adults; it increases in frequency as we age. In Canada, there are more than 1,200 new cases each year. The five-year survival ranges between 20% – 30% and is lower in older people.

The study authors write that using the LSC17 score to single out high-risk patients predicted to have resistant disease “provides clinicians with a rapid and powerful tool to identify AML patients who are less likely to be cured by standard therapy and who could be enrolled in trials evaluating novel upfront or post-remission strategies.”

The researchers identified the LSC17 score by sampling the leukemia stem cell properties of blood or bone marrow samples from 78 AML patients from the cancer centre combined with molecular profiling technology that measures gene expression. Stanley W. K. Ng, a senior PhD candidate in the lab of Dr. Peter Zandstra at the Institute for Biomaterials and Biomedical Engineering, University of Toronto and co-lead author of the paper, used rigorous statistical approaches to develop and test the new “stemness score”, using AML patient data provided by the Princess Margaret leukemia clinic and collaborators in the United States and Europe.

“We identified the minimal set of genes that were most critical for predicting survival in these other groups of AML patients, regardless of where they were treated. With this core 17-gene score, we have shown we can rapidly measure risk in newly diagnosed AML patients,” says Dr. Wang.

In the study, analysis of patient samples demonstrated that high LSC17 scores meant poor outcomes with current standard treatment, even for patients who had undergone allogeneic stem cell transplantation. A low score indicated a patient would respond well to standard treatment and have a long-term remission.

The test to measure the LSC17 score has been adapted to a technology platform called NanoString. As the research team and international collaborators continue to validate the stemness risk score, plans are under way to test the score in a clinical trial at the Princess Margaret, which now has the NanoString system in its molecular diagnostic laboratory.

Dr. Wang explains that the fast turnaround time to measure the LSC17 score on the NanoString system will be key to moving the test into the clinic.

“The LSC17 score is the most powerful predictive and prognostic biomarker currently available for AML, and is the first stem cell-based biomarker developed in this way for any human cancer,” says Dr. Wang. “Clinicians will now have a tool that they can use upfront to tailor treatment to risk in AML.”

The research was funded by the Ontario Institute for Cancer Research, the Cancer Stem Cell Consortium via Genome Canada and the Ontario Genomics Institute; the Canadian Institutes of Health Research, Canadian Cancer Society, Terry Fox Foundation; the Canada Research Chair in Stem Cell Biology (Dr. John Dick), the Leukemia & Lymphoma Society of Canada, the Stem Cell Network, the Orsino Chair in Leukemia Research (Dr. Mark Minden), The Princess Margaret Cancer Foundation, and the Ontario Ministry of Health and Long-Term Care. This work was made possible by the generous contributions of blood and bone marrow samples by AML patients to research.

Dysfunction In Neuronal Transport Mechanism Linked To Alzheimer’s Disease

Researchers at University of California San Diego School of Medicine have confirmed that mutation-caused dysfunction in a process cells use to transport molecules within the cell plays a previously suspected but underappreciated role in promoting the heritable form of Alzheimer’s disease (AD), but also one that might be remedied with existing therapeutic enzyme inhibitors.

The findings published in the October 11 online issue of Cell Reports.

“Our results further illuminate the complex processes involved in the degradation and decline of neurons, which is, of course, the essential characteristic and cause of AD,” said the study’s senior author Larry Goldstein, PhD, Distinguished Professor in the Departments of Neuroscience and Cellular and Molecular Medicine at UC San Diego School of Medicine and director of both the UC San Diego Stem Cell Program and Sanford Stem Cell Clinical Center at UC San Diego Health. “But beyond that, they point to a new target and therapy for a condition that currently has no proven treatment or cure.”

Alzheimer’s disease is a neurodegenerative disorder characterized by progressive memory loss and cognitive dysfunction. It affects more than 30 million people worldwide, including an estimated 5.4 million Americans. One in 10 persons over the age of 65 has AD; one in three over the age of 85. There are currently no treatments proven to cure or reduce the progression of AD.

Genetically, AD is divided into two groups: the much more common sporadic (sAD) form of the disease in which the underlying primary cause is not known and the rarer familial (fAD) form, produced by inherited genetic mutations. In both forms, the brains of AD patients feature accumulations of protein plaques and neurofibrillary tangles that lead to neuronal impairment and eventual cell death.

The prevailing “amyloid cascade hypothesis” posits that these plaques and tangles are comprised, respectively, of amyloid precursor protein (APP) fragments and tau proteins that fuel cellular stress, neurotoxicity, loss of function and cell death. There has been some evidence, however, of another disease-driver: defects in endocytic trafficking — the process by which cells package large, external molecules into vesicles or membrane-bound sacs for transport into the cell for a variety of reasons or uses.

But previous research focused on non-neuronal cells and did not examine the effects of normal expression levels of AD-related proteins, leaving it unclear to what degree decreased endocytosis and other molecular movement within cells played a causative role.

Goldstein and colleagues analyzed neurons created from induced pluripotent stem cells in which they generated PS1 and APP mutations characteristic of fAD using the emerging genome editing technologies CRISPR and TALEN. In this “disease-in-a-dish” approach, they found that the mutated neurons displayed altered distribution and trafficking of APP and internalized lipoproteins (proteins that combine with or transport fat and other lipids in blood plasma). Specifically, there were elevated levels of APP in the soma or cell body while levels were reduced in the neuronal axons.

In previous work, Goldstein’s team had demonstrated that PS1 and APP mutations impaired the activity of specific cellular enzymes. In the latest work, they found that treating mutated fAD neurons with a beta-secretase inhibitor rescued both endocytosis and transcytosis (molecule movement within a cell) functions.

Researchers Find Fertility Genes Required For Sperm Stem Cells

The underlying cause of male infertility is unknown for 30 percent of cases. In a pair of new studies, researchers at University of California San Diego School of Medicine determined that the reproductive homeobox (RHOX) family of transcription factors — regulatory proteins that activate some genes and inactivate others — drive the development of stem cells in the testes in mice. The investigators also linked RHOX gene mutations to male infertility in humans. The mouse study is published September 27 byCell Reports and the human study was published September 15 by Human Molecular Genetics.

“Infertility in general, and especially male fertility, gets little attention considering how common of a problem it is — about 15 percent of couples are affected, and nearly half of these cases are due to male infertility,” said Miles Wilkinson, PhD, professor of reproductive medicine at UC San Diego School of Medicine and senior author of the Cell Reports study. “That means around 7 percent of all males of reproductive age — nearly 4 million men in the U.S. — have fertility problems.” Wilkinson is also a co-author of theHuman Molecular Genetics study, which was led by Jörg Gromoll, PhD, at the University of Münster in Germany.

Sperm are made from cells that undergo many stages. Transcription factors have been identified that direct most of these cell stages, from the dividing cells in the embryo to the cells that rearrange and partition the chromosomes to individual “pre-sperm” in the testes. However, before this latest research, Wilkinson said no transcription factors were known to direct one of the most critical stages — the formation of the stem cells in the testes, known as spermatogonial stem cells.

In the Cell Reports study, Wilkinson and team removed the entire cluster of 33 Rhox genes in mice. They were surprised to find that the most notable defect in these mice was a deficiency in spermatogonial stem cells. Hye-Won Song, PhD, assistant project scientist in Wilkinson’s lab and first author of the Cell Reports study, removed just one of the Rhoxgenes — Rhox10 – and found essentially the same defect as deleting the full set.

Wilkinson, Song and team discovered there was nothing wrong with the spermatogonial stem cells in mice lacking Rhox10, only that there were so few. They found that this occurred because most of the earlier stage cells — pro-spermatogonia — did not specialize into spermatogonial stem cells. As a result, the testes of Rhox10-deficient mice did not enlarge and their sperm counts failed to increase as they aged.

The researchers concluded that Rhox10 is the most critical gene in the Rhox cluster, and that it plays a role in spermatogonial stem cell formation.

The Rhox genes are on the X chromosome. It makes sense that male infertility would be caused by mutated genes on the X chromosome, Wilkinson said, because men only have one copy — if something goes wrong with an X-linked gene, they don’t have a backup, like women do.

There are several potential clinical implications of these results, the researchers said. For example, Rhox genes may have roles in testicular tumors that arise from germ cells that failed to convert into spermatogonial stem cells and thus are “frozen” at the pro-spermatogonia stage. Rhox genes may also be useful for regenerative medicine approaches to restoring fertility through therapy with spermatogonial stem cells.

In the second study, published by Human Molecular Genetics, Gromoll and colleagues sequenced RHOX genes in 250 men with severely low sperm count. They found two mutations in one of these genes (RHOXF1) and four mutations in the other two (RHOXF2and RHOXF2B, which are almost identical). Only one mutation was also found in a control group of men with normal sperm concentrations.

In laboratory experiments, the researchers found that one of the low sperm count-associated mutations significantly impaired transcription factor RHOXF2/2B’s ability to regulate its target genes. Molecular modeling suggested that this mutation altered its 3-D structure.

“Spermatogonial stem cells allow men — even in their 70s — to generate sperm and father children,” said Song, who also co-authored the Human Molecular Genetics study. “Our finding that Rhox10 is critical for spermatogonial stem cells, coupled with the finding that human RHOX genes are mutated in infertile men, suggests that mutations in these genes cause human male infertility.”

This conclusion is further underscored by the previous finding that men with abnormal sperm characteristics tend to have RHOX genes excessively marked with chemical tags known as methyl groups. Wilkinson, Song and team are now working to better understand precisely how variations in RHOX transcription factors lead to human infertility.

Scientists Find Culprit Responsible For Calcified Blood Vessels In Kidney Disease

Scientists have implicated a type of stem cell in the calcification of blood vessels that is common in patients with chronic kidney disease. The research will guide future studies into ways to block minerals from building up inside blood vessels and exacerbating atherosclerosis, the hardening of the arteries.

The study, led by researchers at Washington University School of Medicine in St. Louis, appears Sept. 8 in the journal Cell Stem Cell.

“In the past, this calcification process was viewed as passive — just mineral deposits that stick to the walls of vessels, like minerals sticking to the walls of water pipes,” said senior author Benjamin D. Humphreys, MD, PhD, director of the Division of Nephrology and an associate professor of medicine. “More recently, we’ve learned that calcification is an active process directed by cells. But there has been a lot of controversy over which cells are responsible and where they come from.”

The cells implicated in clogging up blood vessels with mineral deposits live in the outer layer of arteries and are called Gli1 positive stem cells, according to the study. Because they are adult stem cells, Gli1 cells have the potential to become different types of connective tissues, including smooth muscle, fat and bone.

Humphreys and his colleagues showed that in healthy conditions, Gli1 cells play an important role in healing damaged blood vessels by becoming new smooth muscle cells, which give arteries their ability to contract. But with chronic kidney disease, these cells likely receive confusing signals and instead become a type of bone-building cell called an osteoblast, which is responsible for depositing calcium.

“We expect to find osteoblasts in bone, not blood vessels,” Humphreys said. “In the mice with chronic kidney disease, Gli1 cells end up resembling osteoblasts, secreting bone in the vessel wall. During kidney failure, blood pressure is high and toxins build up in the blood, promoting inflammation. These cells may be trying to perform their healing role in responding to injury signals, but the toxic, inflammatory environment somehow misguides them into the wrong cell type.”

The researchers also studied donated tissue from patients who died of kidney failure and who showed calcification in the aorta, the body’s largest artery.

“We found Gli1 cells in the the calcified aortas of patients in exactly the same place we see these cells in the mice,” Humphreys said. “This is evidence that the mice are an accurate model of the disease in people.”

About 20 million adults in the U.S. have some degree of chronic kidney disease, according to the Centers for Disease Control and Prevention. But most of these patients never develop late-stage kidney failure that requires dialysis or kidney transplantation because they succumb to cardiovascular disease first, Humphreys said. The buildup of plaque in the arteries that is characteristic of cardiovascular disease is worsened in patients with diseased kidneys because of the additional mineral deposits.

Further supporting the argument that Gli1 cells are driving the calcification process, Humphreys and his colleagues showed that removing these cells from adult mice prevented the formation of calcium in their blood vessels.

“Now that we have identified Gli1 cells as responsible for depositing calcium in the arteries, we can begin testing ways to block this process,” Humphreys said. “A drug that works against these cells could be a new therapeutic way to treat vascular calcification, a major killer of patients with kidney disease. But we have to be careful because we believe these cells also play a role in healing injured smooth muscle in blood vessels, which we don’t want to interfere with.”

Humphreys is continuing to focus on the kidney in studying ways to guide Gli1 cells away from bone-building osteoblasts and toward vessel-healing smooth muscle cells. The study’s first author, Rafael Kramann, MD, a former postdoctoral researcher in Humphreys’ lab and who is now at Aachen University in Germany, is studying the same process with a focus on the heart.

Stem Cell Breakthrough Unlocks Mysteries Associated With Inherited And Sometimes Lethal Heart Conditions

Using advanced stem cell technology, scientists from the Icahn School of Medicine at Mount Sinai have created a model of a heart condition called hypertrophic cardiomyopathy (HCM) — an excessive thickening of the heart that is associated with a number of rare and common illnesses, some of which have a strong genetic component. The stem cell lines scientists created in the lab, which are believed to closely resemble human heart tissue, have already yielded insights into unexpected disease mechanisms, including the involvement of cells that have never before been linked to pathogenesis in a human stem-cell model of HCM. The research was published in the journal Stem Cell Reports.

The genetic disorder discussed in the new study is called cardiofaciocutaneous syndrome (CFC), which is caused by a mutation in a gene called BRAF. The condition is rare and affects fewer than 300 people worldwide, according to the National Institutes of Health. It causes abnormalities of the head, face, skin, and major muscles, including the heart.

To learn more about HCM associated with various genetic diseases, Mount Sinai scientists took skin cells from three CFC patients and turned them into highly versatile stem cells, which were then converted into cells responsible for the beating of the heart. This model has relevance for research on several related and more common genetic disorders, including Noonan syndrome, which is characterized by unusual facial features, short stature, heart defects, and skeletal malformations.

“At present, there is no curative option for HCM in patients with these related genetic conditions,” said Bruce D. Gelb, MD, Director of The Mindich Child Health and Development Institute and Professor in the Departments of Pediatrics, Genetics and Genomic Sciences at the Icahn School of Medicine at Mount Sinai. “If our findings are correct, they suggest we might be able to treat HCM by blocking specific cell signals—which is something we know how to do.”

Dr. Gelb says that about 40 percent of patients with CFC suffer from HCM (two of the three study participants had HCM). This suggests a pathogenic connection, though the link has never been fully explored or explained. The primary goal of the current research was to understand the role of a cell-signaling pathway called RAS/MAPK in the cascade of events leading to HCM in patients with CFCs — and by association, with Noonan syndrome, Costello syndrome, and other similar illnesses.

Observing the disease progression in these heart cells, called cardiomyocytes, Dr. Gelb and his team found that some of the changes were caused by interactions with cells that resemble fibroblasts — the same kinds of cells that produce collagen and other proteins. Fibroblasts make up a significant portion of total heart tissue, although it is the cardiomyocytes that are primarily responsible for pumping blood. “These fibroblast-like cells seem to be producing an excess of a protein growth factor called TGF-beta, which, in turn, caused the cardiomyocytes to hypertrophy, or grow larger,” Dr. Gelb said. “We believe this is the first time the phenomenon has been observed using a human induced pluripotent stem cell model of the disease.”

Prior to this observation, Dr. Gelb and his team assumed hypertrophy was “cell autonomous,” meaning intrinsic to the cardiomyocytes themselves. “Based on our cell culture model, we saw that fibroblasts are playing a key role in giving the heart cells the signal that causes them to get big,” Dr. Gelb said. “That was quite unexpected.”

The therapeutic implications may also be profound. “We were able to block TGF-beta in vitro using antibodies that bind to the protein. When we did that, the cardiomyocytes no longer hypertrophy,” Dr. Gelb said. It’s not certain the same effect would be seen in the many clinical cases of HCM that are not influenced by BRAF or the RAS pathway—essentially a chain of cellular proteins that help transmit signals from surface receptors on the cell to DNA in the nucleus –but researchers believe this could be the case.

The bigger surprise, said Dr. Gelb, “is that we may be talking about a signaling circle” in which fibroblasts trigger the release of a growth factor, which causes cardiomyocytes to hypertrophy, which in turn, prompts fibroblasts to release more of the growth factor.” Dr. Gelb didn’t witness this last part of the circle in his stem cell culture, but evidence of fibroblast stimulation has been reported in mouse models that don’t express the RAS mutation. If the circle theory is validated, Dr. Gelb said, there could be new and broad therapeutic interventions for HCM in both RAS and non-RAS contexts. “In theory, at least, a therapy could be useful for both,” he said.

Body’s Own Gene Editing System Generates Leukemia Stem Cells

Cancer stem cells are like zombies — even after a tumor is destroyed, they can keep coming back. These cells have an unlimited capacity to regenerate themselves, making more cancer stem cells and more tumors. Researchers at University of California San Diego School of Medicine have now unraveled how pre-leukemic white blood cell precursors become leukemia stem cells. The study, published June 9 in Cell Stem Cell, used human cells to define the RNA editing enzyme ADAR1’s role in leukemia, and find a way to stop it.

While DNA is like the architect’s blueprint for a cell, RNA is the like the engineer’s interpretation of the blueprint. That RNA version is frequently flawed in cancer. While many studies have uncovered pivotal DNA mutations in cancer, few have addressed the roles of RNA and mechanisms that regulate RNA.

“In this study, we showed that cancer stem cells co-opt a RNA editing system to clone themselves. What’s more, we found a method to dial it down,” said senior author Catriona Jamieson, MD, PhD, associate professor of medicine and chief of the Division of Regenerative Medicine at UC San Diego School of Medicine.

The enzyme at the center of this study, ADAR1, can edit the sequence of microRNAs, small pieces of genetic material. By swapping out just one microRNA building block for another, ADAR1 alters the carefully orchestrated system cells use to control which genes are turned on or off at which times.

ADAR1 is known to promote cancer progression and resistance to therapy. In this study, Jamieson’s team used human blast crisis chronic myeloid leukemia cells in the lab, and mice transplanted with these cells, to determine ADAR1’s role in governing leukemia stem cells.

The researchers uncovered a series of molecular events. First, white blood cells with a leukemia-promoting gene mutation become more sensitive to signs of inflammation. That inflammatory response activates ADAR1. Then, hyper-ADAR1 editing slows down the microRNAs known as let-7. Ultimately, this activity increases cellular regeneration, or self-renewal, turning white blood cell precursors into leukemia stem cells. Leukemia stem cells promote an aggressive, therapy-resistant form of the disease called blast crisis.

“This is the first mechanistic link between pro-cancer inflammatory signals and RNA editing-driven reprogramming of precursor cells into leukemia stem cells,” said Jamieson, who is also deputy director of the Sanford Stem Cell Clinical Center at UC San Diego Health, director of the CIRM Alpha Stem Cell Clinic at UC San Diego School of Medicine and director of stem cell research at UC San Diego Moores Cancer Center.

After learning how the ADAR1 system works, Jamieson’s team looked for a way to stop it. By inhibiting sensitivity to inflammation or inhibiting ADAR1 with a small molecule tool compound, the researchers were able to counter ADAR1’s effect on leukemia stem cell self-renewal and restore let-7. Self-renewal of blast crisis chronic myeloid leukemia cells was reduced by approximately 40 percent when treated with the small molecule, called 8-Aza, as compared to untreated cells.

“Based on this research, we believe that detecting ADAR1 activity will be important for predicting cancer progression. In addition, inhibiting this enzyme represents a unique therapeutic vulnerability in cancer stem cells with active inflammatory signaling that may respond to pharmacologic inhibitors of inflammation sensitivity or selective ADAR1 inhibitors that are currently being developed,” Jamieson said.

Stem Cells From Diabetic Patients Coaxed to Become Insulin-Secreting Cells

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.

The research is published May 10 in the journal Nature Communications.

“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.

First Skin-to-Eye Stem Cell Transplant in Humans Successful

Researchers have safely transplanted stem cells derived from a patient’s skin to the back of the eye in an effort to restore vision. The research is being presented at the 2016 Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO) this week in Seattle, Wash.

A small piece of skin from the patient’s arm was collected and modified into induced pluripotent stem cells (iPSC). The iPSCs were then transformed into eye cells, which were transplanted into the patient’s eye. The transplanted cells survived without any adverse events for over a year and resulted in slightly improved vision. The patient suffered from advanced wet age-related macular degeneration (AMD) that did not respond to current standard treatments.

iPSCs are adult cells that have been reprogrammed to an embryonic stem cell-like state, which can then be differentiated into any cell type found in the body.

Cell Transplant Treats Parkinson’s in Mice Under Control of Designer Drug

A University of Wisconsin-Madison neuroscientist has inserted a genetic switch into nerve cells so a patient can alter their activity by taking designer drugs that would not affect any other cell. The cells in question are neurons and make the neurotransmitter dopamine, whose deficiency is the culprit in the widespread movement disorder Parkinson’s disease.

Dopamine is a brain chemical essential for coordinated movement. Dopamine replacement, a standard therapy for Parkinson’s disease, usually loses its effect with time and, with the advent of stem cell technology, biomedical researchers have explored the notion of making dopamine-producing cells in the lab for transplant. And while doctors have tested dopamine cell transplants, the therapy often fails when the transplanted cells make either too much or too little of the essential neurotransmitter.

In a study published April 28 in the journal Cell Stem Cell, Su-Chun Zhang, a professor of neuroscience at the UW-Madison Waisman Center, created two related cell types. When they detect the designer drug, one type ramps up production of dopamine; the other chokes it off.

Zhang and co-first authors Yuejun Chen and Man Xiong grew the specialized nerve cells from human embryonic stem cells, which are able to form any of the 220 cell types in the human body. Their behavioral tests, designed to show when the Parkinson’s symptoms abated in the mice, confirmed that both the “up” and “down” switches performed as anticipated. The results suggest that it may one day be possible to resume dopamine neuron transplants to assist Parkinson’s disease patients.

But the ability to transplant cells that respond to regulatory drugs could have much wider application, says Zhang, who pioneered the transformation of embryonic stem cells into neural cells. “I’m a neuro guy, and the Parkinson’s disease model is very well established in mice — you can measure the outcome in their behavior. If the animal recovers, it must be due to the secretion of dopamine from the transplanted cell.”

Cells tend to have quite specific actions, and the ability to control them with benign drugs could find other uses, Zhang says. In diabetes, for example, “perhaps the beta cells that secrete insulin could be transplanted, and the patients could control insulin secretion with a designer drug.”

The current advance was built with a new, highly precise form of “gene editing” called CRISPR. The new technique replaces the scattershot method of moving genes with something that resembles the “find and replace” command in a word processor that puts the insertion only at the desired location.

Cell therapy was one of the most touted potential benefits of embryonic stem cells and the stem cells that were later derived from adult tissue (both technologies pioneered at UW-Madison), but few applications have reached the clinic as the technology continues to be refined and made safer. Control is part of the problem, Zhang says: “If we are going to use cell therapy, we need to know what the transplanted cell will do. If its activity is not right, we may want to activate it, or we may need to slow or stop it.”

The mouse study showed both abilities, says Zhang, who anticipates that cells will also be engineered to contain switches that work in both directions.

Several major steps will be needed before the first clinical trial can be started. These include:
—Proving the safety of the genetically engineered stem cells, and of the drugs used for control purposes.
—Choosing transplants with maximum potential for natural, neural control of dopamine secretion.
—Ensuring that the neurons reach the brain location where dopamine is needed to control movement.
—Passing nonhuman primate studies. “We need to prove that this is not just a mouse phenomenon,” Zhang says, “that this really works to alleviate the symptoms of Parkinson’s disease.”
Such studies are already underway, he adds.

Despite those hurdles, Zhang considers the discovery one the most exciting in his substantial record of scientific firsts. After the engineered cells are transplanted into the mouse brain, he says, “we can turn them on or off, up or down, using a designer drug that can only act on cells that express the designer receptor. The drug does not affect any host cell because they don’t have that specialized receptor. It’s a very clean system.”

The study shows, for the first time with a human stem cell transplant, that because of this new technology of gene editing, you can remotely regulate the function of the transplanted cell, one that is reversible. If you take away the drug, it comes back.

Many other conditions could benefit from this approach, Zhang says. “This is the first proof of principle, using Parkinson’s disease as the model, but it may apply to many other diseases, and not just neurological diseases.”

Stem Cell Study Finds Mechanism That Controls Skin and Hair Color

A pair of molecular signals controls skin and hair color in mice and humans — and could be targeted by new drugs to treat skin pigment disorders like vitiligo, according to a report by scientists at NYU Langone Medical Center.

Finding ways to activate these pathways, researchers say, could lead to therapies that repigment skin cells damaged in vitiligo, a disfiguring illness marked by the loss of skin pigmentation, leaving a blotchy, white appearance. The same pathways could serve as targets for drug therapies that repigment grayed hair cells for people seeking a younger look but who are allergic to cosmetic dyes. Such therapies might even one day reinforce pigment to correct discoloration around scars.

In experiments in mice and human cells, researchers found that control of these skin and early-stage hair cells, known as melanocyte stem cells, is regulated by cell-to-cell signaling reactions. These reactions are part of the endothelin receptor type B (EdnrB) and the Wnt signaling pathways.

Previous research had shown that endothelin proteins and the EdnrB pathway help control blood vessel development, as well as some aspects of cell growth and division, the scientists say. But they believe that their new findings, to be published in the journal Cell Reports online April 28, are the first evidence tying the signaling pathways to the routine growth of cells that produce pigment (melanocytes) and provide color to skin and hair.

They say the study is the first to outline the link between EdnrB and Wnt signaling, confirming that EdnrB coordinates the rapid reproduction of melanocyte stem cells.

“Our study results show that EdnrB signaling plays a critical role in growth and regeneration of certain pigmented skin and hair cells and that this pathway is dependent on a functioning Wnt pathway,” says study senior investigator and cell biologist Mayumi Ito, PhD. Ito is an associate professor in the Ronald O. Perelman Department of Dermatology at NYU Langone and a member of NYU Langone’s Helen L. and Martin S. Kimmel Center for Stem Cell Biology.

Among the study’s key findings, Ito reports, was that mice bred to be deficient in the EdnrB pathway experienced premature graying of their fur.

Study co-lead investigator and postdoctoral fellow Wendy Lee, PhD, says the pathway’s involvement in determination of hair color was “clearly evident” in the mice when she first examined them.

In further experiments in mice, stimulating the EdnrB pathway resulted in a 15-fold increase in melanocyte stem cell pigment production within two months, producing what Ito calls “hyperpigmentation.” Wounded skin in normally white mice became dark upon healing.

In the latest study, Ito and her team found that blocking Wnt signaling stalled stem cell growth and the maturing of stem cells into normally functioning melanocytes, even when endothelin proteins were present. This led to mice with unpigmented grayish coats.

Ito says her team plans further investigations into how other cell repair and signaling pathways interact with EdnrB and melanocyte stem cells.

According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, vitiligo occurs in about 1 percent of people worldwide.

Growing skin in the lab

Using reprogrammed iPS cells, scientists from the RIKEN Center for Developmental Biology (CDB) in Japan have, along with collaborators from Tokyo University of Science and other Japanese institutions, successfully grown complex skin tissue–complete with hair follicles and sebaceous glands–in the laboratory. They were then able to implant these three-dimensional tissues into living mice, and the tissues formed proper connections with other organ systems such as nerves and muscle fibers. This work opens a path to creating functional skin transplants for burn and other patients who require new skin.

Research into bioengineered tissues has led to important achievements in recent years–with a number of different tissue types being created–but there are still obstacles to be overcome. In the area of skin tissue, epithelial cells have been successfully grown into implantable sheets, but they did not have the proper appendages–the oil-secreting and sweat glands–that would allow them to function as normal tissue.

To perform the work, published in Science Advances, the researchers took cells from mouse gums and used chemicals to transform them into stem cell-like iPS cells. In culture, the cells properly developed into what is called an “embryoid body” (EB) a three-dimensional clump of cells that partially resembles the developing embryo in an actual body. The researchers created EBs from iPS cells using Wnt10b signaling and then implanted multiple EBs into immune-deficient mice, where they gradually changed into differentiated tissue, following the pattern of an actual embryo. Once the tissue had differentiated, the scientists transplanted them out of those mice and into the skin tissue of other mice, where the tissues developed normally as integumentary tissue, the tissue between the outer and inner skin that is responsible for much of the function of the skin in terms of hair shaft eruption and fat excretion. Critically, they also found that the implanted tissues made normal connections with the surrounding nerve and muscle tissues, allowing it to function normally.

One important key to the development was that treatment with Wnt10b, a signaling molecule, resulted in a larger number of hair follicles, making the bio-engineered tissue closer to natural tissue.

“Up until now, artificial skin development has been hampered by the fact that the skin lacked the important organs, such as hair follicles and exocrine glands, which allow the skin to play its important role in regulation. With this new technique, we have successfully grown skin that replicates the function of normal tissue. We are coming ever closer to the dream of being able to recreate actual organs in the lab for transplantation, and also believe that tissue grown through this method could be used as an alternative to animal testing of chemicals,” according to Takashi Tsuji of the RIKEN Center for Developmental Biology, who led the study.