Diseased hearts to heal themselves in future

Diseased hearts to heal themselves in future

  10:08:00 AM    Science Lover

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Cellular reversion processes arise in diseases of the heart muscle, for example myocardial infarction and cardiomyopathy, which limit the fatal consequences for the organ. Scientists from the Max Planck Institute for Heart and Lung Research in Bad Nauheim and the Schüchtermann Klinik in Bad Rothenfelde have identified a protein which fulfils a central task in this reversion process by stimulating the regression of individual heart muscle cells into their precursor cells. It is now planned to improve the self-healing powers of the heart with the help of this protein.

Cellular regression in diseased heart tissue with the help
of oncostatin M: The image shows heart muscles under
the fluorescence microscope. The myofibrils are stained
red, the cell nuclei blue.
Credit: MPI for Heart and Lung Research

In order to regenerate damaged heart muscle as caused by a heart attack, for example, the damaged muscle cells must be replaced by new ones. The number of cells to be replaced may be considerable, depending on the extent of the damage caused. Simpler vertebrates like the salamander adopt a strategy whereby surviving healthy heart muscle cells regress into an embryonic state. This process, which is known as dedifferentiation, produces cells which contain a series of stem cell markers and re-attain their cell division activity. Thus, new cells are produced which convert, in turn, into heart muscle cells. The cardiac function is then restored through the remodelling of the muscle tissue.

An optimised repair mechanism of this kind does not exist in humans. Although heart stem cells were discovered some time ago, exactly how and to what extent they play a role in cardiac repair is a matter of dispute. It has only been known for a few years that processes comparable to those found in the salamander even exist in mammals.

Thomas Braun's research group at the Max Planck Institute for Heart and Lung Research in Bad Nauheim has now discovered the molecule responsible for controlling this dedifferentiation of heart muscle cells in mammals. The scientists initially noticed the high concentration of oncostatin M in tissue samples from the hearts of patients suffering from myocardial infarction. It was already known that this protein is responsible for the dedifferentiation of different cell types, among other things. The researchers therefore treated cultivated heart muscle cells with oncostatin M in the laboratory and were then able to trace the regression of the cells live under the microscope: "Based on certain changes in the cells, we were able to see that almost all heart muscle cells had been dedifferentiated within six days of treatment with oncostatin M," explains Braun. "We were also able to demonstrate the presence of various stem cell markers in the cells. This should be understood as an indicator that these cells had been switched to a repair mode."

Using a mouse infarct model, the Max Planck researchers succeeded in demonstrating that oncostatin M actually does stimulate the repair of damaged heart muscle tissue as presumed. One of the two test groups had been modified genetically in advance to ensure that the oncostatin M could not have any effect in these animals. "The difference between the two groups was astonishing. Whereas in the group in which oncostatin M could take effect almost all animals were still alive after four weeks, 40 percent of the genetically modified mice had died from the effects of the infarction," says Braun. The reason for this was that oncostatin M ensured clearly quantifiable better cardiac function in the unmodified animals.

The scientists in Bad Nauheim would now like to find a way of using oncostatin M in treatment. The aim is to strengthen the self-healing powers of the damaged heart muscle and to enable the restoration of cardiac function for the first time. The downside, however, is that oncostatin M was also observed to be counterproductive and exacerbated the damage in an experiment on a chronically diseased heart. "We believe that oncostatin M has considerable potential for efficiently healing damaged heart muscle tissue. What we now need is to be able to pinpoint the precise window of application to prevent any possible negative effects," says Braun.
More information: Thomas Kubin, Jochen Pöling, Sawa Kostin, Praveen Gajawada, Stefan Hein, Wolfgang Rees, Astrid Wietelmann, Minoru Tanaka, Holger Lörchner, Silvia Schimanski, Marten Szibor, Henning Warnecke, Thomas Braun: Oncostatin M Is a Major Mediator of Cardiomyocyte Dedifferentiation and Remodeling. Cell Stem Cell 9, 420, 2011

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Scientists successfully expand bone marrow-derived stem cells in culture

Scientists successfully expand bone marrow-derived stem cells in culture

  8:13:00 PM    Science Lover

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All stem cells-regardless of their source-share the remarkable capability to replenish themselves by undergoing self-renewal. Yet, so far, efforts to grow and expand scarce hematopoietic (or blood-forming) stem cells in culture for therapeutic applications have been met with limited success.

An image of fully functional hematopoietic
stem cells (or blood-forming) that are successfully

proliferating amongst other bone marrow-derived

cells in a culture dish. Credit: Dr. John Perry,
Stowers Institute forMedical Research

Now, researchers at the Stowers Institute for Medical Research teased apart the molecular mechanisms enabling stem cell renewal in hematopoietic stem cells isolated from mice and successfully applied their insight to expand cultured hematopoietic stem cells a hundredfold.

Their findings, which will be published in the Sept. 15, 2011, edition of Genes & Development, demonstrate that self-renewal requires three complementary events: proliferation, active suppression of differentiation and programmed cell death during proliferation.

"The previous efforts so far to grow and expand scarce hematopoietic stem cells in culture for therapeutic applications have been met with limited success", says Stowers investigator Linheng Li, Ph.D., who led the study. "Being able to tap into stem cell's inherent potential for self-renewal could turn limited sources of hematopoietic stem cells such as umbilical cord blood into more widely available resources for hematopoietic stem cells," he adds while cautioning that their findings have yet to be replicated in human cells.

The transplantation of human hematopoietic stem cells isolated from bone marrow is used in the treatment of anemia, immune deficiencies and other diseases, including cancer. However, since bone marrow transplants require a suitable donor-recipient tissue match, the number of potential donors is limited.

Hematopoietic stem cells isolated from umbilical cord blood could be a good alternative source: Readily available and immunologically immature, they allow the donor-recipient match to be less than perfect without the risk of immune rejection of the transplant. Unfortunately, their therapeutic use is limited since umbilical cord blood contains only a small number of stem cells.

Although self-renewal is typically considered a single trait of stem cells, Li and his team wondered whether it could be pulled apart into three distinct requirements: proliferation, maintenance of the undifferentiated state, and the suppression of programmed cell death or apoptosis. "The default state of stem cells is to differentiate into a specialized cell types," explains postdoctoral researcher and first author John Perry, Ph.D. "Differentiation must be blocked in order for stem cells to undergo self-renewal."




Proliferation of stem cells in an undifferentiated state, however, calls tumor suppressor genes into action. These genes help prevent cancer by inducing a process of cell death known as apoptosis. "Consequently, self-renewal of adult stem cells must also include a third event, the active suppression of apoptosis," says Perry.

To test their hypothesis, Perry and his colleagues isolated hematopoietic stem cells from mice and analyzed two key genetic pathways—the Wnt/β-catenin and PI3K/Akt pathways. Wnt proteins had been identified as "self-renewal factors," while PI3K/Akt activation had been shown to induce proliferation and promote survival by inhibiting apoptosis.

Surprisingly, activation of the Wnt/β-catenin pathway alone blocked differentiation but eventually resulted in cell death, while activation of the PI3K/Akt pathway alone increased differentiation but facilitated cell survival. Only when both pathways were activated, did the pool of hematopoietic stem cells start expanding. "This demonstrated both pathways had to cooperate to promote self-renewal," says Perry.

Although altering both pathways drives self-renewal of hematopoietic stem cells, it also permanently blocks their ability to mature into fully functional blood cells. To sidestep the differentiation block and generate normal, functioning hematopoietic stem cells usable for therapy, the Stowers scientists used small molecules to reversibly activate both the Wnt/β-catenin and PI3K/Akt pathways in culture.

"We were able to expand the most primitive hematopoietic stem cells, which, when transplanted back into mice gave rise to all blood cell types throughout three, sequential transplantation experiments," says Li. "If similar results can be achieved using human hematopoietic stem cells from sources such as umbilical cord blood, this work is expected to have substantial clinical impact."

Provided by Stowers Institute for Medical Research

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New Treatments for Baldness? Scientists Find Stem Cells That Tell Hair It's Time to Grow

New Treatments for Baldness? Scientists Find Stem Cells That Tell Hair It's Time to Grow

  12:41:00 AM    Science Lover

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Yale researchers have discovered the source of signals that trigger hair growth, an insight that may lead to new treatments for baldness.

Researchers have discovered the source of signalsthat 
trigger hair growth, an insight that may lead to new 
treatments for baldness. (Credit: © Tasosk / Fotolia)

The researchers identified stem cells within the skin's fatty layer and showed that molecular signals from these cells were necessary to spur hair growth in mice, according to research published in the Sept. 2 issue of the journal Cell.

"If we can get these fat cells in the skin to talk to the dormant stem cells at the base of hair follicles, we might be able to get hair to grow again," said Valerie Horsley, assistant professor of molecular, cellular and developmental biology and senior author of the paper.

Men with male pattern baldness still have stem cells in follicle roots but these stem cells lose the ability to jump-start hair regeneration. Scientists have known that these follicle stem cells need signals from within the skin to grow hair, but the source of those signals has been unclear.




Horsley's team observed that when hair dies, the layer of fat in the scalp that comprises most of the skin's thickness shrinks. When hair growth begins, the fat layer expands in a process called adipogenesis. Researchers found that a type of stem cell involved in creation of new fat cells -- adipose precursor cells -- was required for hair regeneration in mice. They also found these cells produce molecules called PDGF (platelet derived growth factors), which are necessary to produce hair growth.

Horsley's lab is trying to identify other signals produced by adipose precursor stem cells that may play a role in regulating hair growth. She also wants to know whether these same signals are required for human hair growth. Other authors from Yale are lead author Eric Festa, Jackie Fretz, Ryan Berry, Barbara Schmidt, Matthew Rodeheffer and Mark Horowitz.

The work was funded by the National Institutes of Health and the Connecticut Stem Cell Research Program.

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Controlling self-renewal of stem cells

Controlling self-renewal of stem cells

  5:03:00 PM    Science Lover

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Scientists from the Friedrich Miescher Institute for Biomedical Research (FMI) are the first to establish a direct link between a conserved stem cell factor and the cell cycle regulation in adult stem cells. As published online in the EMBO Journal, they demonstrated that the self-renewal of C. elegans germline stem cells requires repression of a cell cycle inhibitor, CKI-2, by a conserved RNA-binding protein, FBF. 

The promise of stem cells is two-fold: On one hand, they can differentiate into all the specialised cells in the tissues of the body and thereby guarantee tissue repair; on the other hand, they can self-renew and form new stem cells ensuring -at least in theory- an inexhaustible supply of cells in demand. However, the molecular processes controlling these traits are still elusive. Thus, a better understanding of stem cell biology is in high demand to be able to deliver eventually on the promise of stem cells in therapy.

From observations scientists have know that stem cells that start to differentiate take longer to divide, their cell cycle is slowed down as if to give the cells enough time to change the program. At the same time, cells that self-renew are pushed through the cell cycle as if to give them no alternative. Despite the growing evidence for the importance of cell-cycle regulation in self-renewal and differentiation, linking critical stem cell factors to the cell cycle regulation in adult stem cells has so far never been possible.



The FMI group leader Rafal Ciosk and his colleagues have now been able to describe for the first time a direct link between proteins controlling stem cell traits and proteins directing the cell cycle. Their results have been published this month online in the EMBO Journal. In their experimental model, the nematode C. elegans, the RNA binding stem cell factor called FBF represses the cell cycle inhibitor CKI-2.This repression is achieved through a direct repression of cki-2 mRNA by FBF. They showed that this mechanism is necessary not only for the self-renewal of stem cells but also to prevent their untimely differentiation. Thus, in the absence of FBF, worms lose their germline stem cells. Once CKI-2 was no longer inhibited in these worms, the cells rushed through the cell cycle and the worms formed germline stem cells again.

"Understanding the processes that determine stem cell characteristics is absolutely critical if we ever want to make use of the full potential of stem cells in therapy. Several lines of evidence have suggested that the decision to self renew or differentiate is closely connected to the cell cycle. We have now been the first to demonstrate this link on a molecular level," comments Ciosk.

More information: Kalchhauser I, et al. (2011) FBF represses the Cip/Kip cell-cycle inhibitor CKI-2 to promote self-renewal of germline stem cells in C. elegans, EMBO J. 2011 Aug 5. doi: 10.1038/emboj.2011.263. [Epub ahead of print]

Provided by Friedrich Miescher Institute for Biomedical Research

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New Genetic Technique Converts Skin Cells Into Brain Cells

New Genetic Technique Converts Skin Cells Into Brain Cells

  6:16:00 PM    Science Lover

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A research breakthrough has proven that it is possible to reprogram mature cells from human skin directly into brain cells, without passing through the stem cell stage. The unexpectedly simple technique involves activating three genes in the skin cells; genes which are already known to be active in the formation of brain cells at the fetal stage.

Photomicrograph of fibroblast cells in tissue culture. 
(Credit: iStockphoto/Torsten Wittmann)

The new technique avoids many of the ethical dilemmas that stem cell research has faced.

For the first time, a research group at Lund University in Sweden has succeeded in creating specific types of nerve cells from human skin. By reprogramming connective tissue cells, called fibroblasts, directly into nerve cells, a new field has been opened up with the potential to take research on cell transplants to the next level. The discovery represents a fundamental change in the view of the function and capacity of mature cells. By taking mature cells as their starting point instead of stem cells, the Lund researchers also avoid the ethical issues linked to research on embryonic stem cells.

Head of the research group Malin Parmar was surprised at how receptive the fibroblasts were to new instructions.

"We didn't really believe this would work, to begin with it was mostly just an interesting experiment to try. However, we soon saw that the cells were surprisingly receptive to instructions." The study, which was published in the latest issue of the Proceedings of the National Academy of Sciences, also shows that the skin cells can be directed to become certain types of nerve cells.

In experiments where a further two genes were activated, the researchers have been able to produce dopamine brain cells, the type of cell which dies in Parkinson's disease. The research findings are therefore an important step towards the goal of producing nerve cells for transplant which originate from the patients themselves. The cells could also be used as disease models in research on various neurodegenerative diseases.



Unlike older reprogramming methods, where skin cells are turned into pluripotent stem cells, known as IPS cells, direct reprogramming means that the skin cells do not pass through the stem cell stage when they are converted into nerve cells. Skipping the stem cell stage probably eliminates the risk of tumours forming when the cells are transplanted. Stem cell research has long been hampered by the propensity of certain stem cells to continue to divide and form tumours after being transplanted.

Before the direct conversion technique can be used in clinical practice, more research is needed on how the new nerve cells survive and function in the brain. The vision for the future is that doctors will be able to produce the brain cells that a patient needs from a simple skin or hair sample. In addition, it is presumed that specifically designed cells originating from the patient would be accepted better by the body's immune system than transplanted cells from donor tissue.

"This is the big idea in the long run. We hope to be able to do a biopsy on a patient, make dopamine cells, for example, and then transplant them as a treatment for Parkinson's disease," says Malin Parmar, who is now continuing the research to develop more types of brain cells using the new technique.

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New genetic technique converts skin cells into brain cells

New genetic technique converts skin cells into brain cells

  12:34:00 AM    Science Lover

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A research breakthrough has proven that it is possible to reprogram mature cells from human skin directly into brain cells, without passing through the stem cell stage. The unexpectedly simple technique involves activating three genes in the skin cells; genes which are already known to be active in the formation of brain cells at the foetal stage.

converts skin cells into brain cells

The new technique avoids many of the ethical dilemmas that stem cell research has faced.

For the first time, a research group at Lund University in Sweden has succeeded in creating specific types of nerve cells from human skin. By reprogramming connective tissue cells, called fibroblasts, directly into nerve cells, a new field has been opened up with the potential to take research on cell transplants to the next level. The discovery represents a fundamental change in the view of the function and capacity of mature cells. By taking mature cells as their starting point instead of stem cells, the Lund researchers also avoid the ethical issues linked to research on embryonic stem cells.

Head of the research group Malin Parmar was surprised at how receptive the fibroblasts were to new instructions.

"We didn't really believe this would work, to begin with it was mostly just an interesting experiment to try. However, we soon saw that the cells were surprisingly receptive to instructions."

The study, which was published in the latest issue of the scientific journal PNAS, also shows that the skin cells can be directed to become certain types of nerve cells.

In experiments where a further two genes were activated, the researchers have been able to produce dopamine brain cells, the type of cell which dies in Parkinson's disease. The research findings are therefore an important step towards the goal of producing nerve cells for transplant which originate from the patients themselves. The cells could also be used as disease models in research on various neurodegenerative diseases.

Unlike older reprogramming methods, where skin cells are turned into pluripotent stem cells, known as IPS cells, direct reprogramming means that the skin cells do not pass through the stem cell stage when they are converted into nerve cells. Skipping the stem cell stage probably eliminates the risk of tumours forming when the cells are transplanted. Stem cell research has long been hampered by the propensity of certain stem cells to continue to divide and form tumours after being transplanted.

Before the direct conversion technique can be used in clinical practice, more research is needed on how the new nerve cells survive and function in the brain. The vision for the future is that doctors will be able to produce the brain cells that a patient needs from a simple skin or hair sample. In addition, it is presumed that specifically designed cells originating from the patient would be accepted better by the body's immune system than transplanted cells from donor tissue.

"This is the big idea in the long run. We hope to be able to do a biopsy on a patient, make dopamine cells, for example, and then transplant them as a treatment for Parkinson's disease", says Malin Parmar, who is now continuing the research to develop more types of brain cells using the new technique.

More information: 'Direct conversion of human fibroblasts to dopaminergic neurons', publ. PNAS 2011; 6 June 2011: http://www.pnas.or … 108.abstract

Provided by Lund University

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Sections of Retinas Regenerated and Visual Function Increased With Stem Cells from Skin

Sections of Retinas Regenerated and Visual Function Increased With Stem Cells from Skin

  1:02:00 PM    Science Lover

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Scientists from Schepens Eye Research Institute are the first to regenerate large areas of damaged retinas and improve visual function using IPS cells (induced pluripotent stem cells) derived from skin. The results of their study, which is published in PLoS ONE this month, hold great promise for future treatments and cures for diseases such as age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy and other retinal diseases that affect millions worldwide.

Histological staining of a teratoma containing Rho-/- eye
at 21 days post-injection of a heterogeneous population of
SSEA1-containing D33 differentiated cells. (Credit: Tucker
et al.,DOI: 10.1371/journal.pone.0018992)

"We are very excited about these results," says Dr. Budd A. Tucker, the study's first author. "While other researchers have been successful in converting skin cells into induced pluripotent stem cells (iPSCs) and subsequently into retinal neurons, we believe that this is the first time that this degree of retinal reconstruction and restoration of visual function has been detected," he adds. Tucker, who is currently an Assistant Professor of Ophthalmology at the University of Iowa, Carver College of Medicine, completed the study at Schepens Eye Research Institute in collaboration with Dr. Michael J. Young, the principle investigator of the study, who heads the Institute's regenerative medicine center.

Today, diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are the leading causes of incurable blindness in the western world. In these diseases, retinal cells, also known as photoreceptors, begin to die and with them the eye's ability to capture light and transmit this information to the brain. Once destroyed, retinal cells, like other cells of the central nervous system have limited capacity for endogenous regeneration.

"Stem cell regeneration of this precious tissue is our best hope for treating and someday curing these disorders," says Young, who has been at the forefront of vision stem cell research for more than a decade.

While Tucker, Young and other scientists were beginning to tap the potential of embryonic and adult stem cells early in the decade, the discovery that skin cells could be transformed into "pluripotent" cells, nearly identical to embryonic cells, stirred excitement in the vision research community. Since 2006 when researchers in Japan first used a set of four "transcription factors" to signal skin cells to become iPSCs, vision scientists have been exploring ways to use this new technology. Like embryonic stem cells, iPSCs have ¬the ability to become any other cell in the body, but are not fraught with the ethical, emotional and political issues associated with the use of tissue from human embryos.

Tucker and Young harvested skin cells from the tails of red fluorescent mice. They used red mice, because the red tissue would be easy to track when transplanted in the eyes of non-fluorescent diseased mice.

By forcing these cells to express the four Yamanaka transcription factors (named for their discoverer) the group generated red fluorescent IPSCs, and, with additional chemical coaxing, precursors of retinal cells. Precursor cells are immature photoreceptors that only mature in their natural habitat -- the eye.

Within 33 days the cells were ready to be transplanted and were introduced into the eyes of a mouse model of retina degenerative disease. Due to a genetic mutation, the retinas of these recipient mice quickly degenerate, the photoreceptor cells die and at the time of transplant electrical activity, as detected by ERG (electroretinography), is absent.

Within four to six weeks, the researchers observed that the transplanted "red" cells had taken up residence in the appropriate retinal area (photoreceptor layer) of the eye and had begun to integrate and assemble into healthily looking retinal tissue.

The team then retested the mice with ERG and found a significant increase in electrical activity in the newly reconstructed retinal tissue. In fact, the amount of electrical activity was approximately half of what would be expected in a normal retina. They also conducted a dark adaption test to see if connections were being made between the new photoreceptor cells and the rest of the retina. In brief, the group found that by stimulating the newly integrated photoreceptor cells with light they could detect a signal in the downstream neurons, which was absent in the other untreated eye.

Based on the results of their study, Tucker and Young believe that harvesting skin cells for use in retinal regeneration is and will continue to be a promising resource for the future.

The two scientists say their next step will be to take this technology into large animal models of retinal degenerative disease and eventually toward human clinical trials.

Other scientists involved in the PLoS ONE study include In-Hyun Park, Sara D. Qi, Henry J. Klassen, Caihui Jiang, Jing Yao, Stephen Redenti, and George Q. Daley.

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Scientists Create Stable, Self-Renewing Neural Stem Cells

Scientists Create Stable, Self-Renewing Neural Stem Cells

  9:35:00 AM    Science Lover

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In a paper published in the April 25 early online edition of the Proceedings of the National Academy of Sciences, researchers at the University of California, San Diego School of Medicine, the Gladstone Institutes in San Francisco and colleagues report a game-changing advance in stem cell science: the creation of long-term, self-renewing, primitive neural precursor cells from human embryonic stem cells (hESCs) that can be directed to become many types of neuron without increased risk of tumor formation.

Depicts cultured, self-renewing primitive neural 
precursors derived from human embryonic stem cells 
using molecule inhibitors. (Credit: UC San 
Diego School of Medicine)

"It's a big step forward," said Kang Zhang, MD, PhD, professor of ophthalmology and human genetics at Shiley Eye Center and director of the Institute for Genomic Medicine, both at UC San Diego. "It means we can generate stable, renewable neural stem cells or downstream products quickly, in great quantities and in a clinical grade -- millions in less than a week -- that can be used for clinical trials and, eventually, for clinical treatments. Until now, that has not been possible."

Human embryonic stem cells hold great promise in regenerative medicine due to their ability to become any kind of cell needed to repair and restore damaged tissues. But the potential of hESCs has been constrained by a number of practical problems, not least among them the difficulty of growing sufficient quantities of stable, usable cells and the risk that some of these cells might form tumors.

To produce the neural stem cells, Zhang, with co-senior author Sheng Ding, PhD, a former professor of chemistry at The Scripps Research Institute and now at the Gladstone Institutes, and colleagues added small molecules in a chemically defined culture condition that induces hESCs to become primitive neural precursor cells, but then halts the further differentiation process.

"And because it doesn't use any gene transfer technologies or exogenous cell products, there's minimal risk of introducing mutations or outside contamination," Zhang said. Assays of these neural precursor cells found no evidence of tumor formation when introduced into laboratory mice.

By adding other chemicals, the scientists are able to then direct the precursor cells to differentiate into different types of mature neurons, "which means you can explore potential clinical applications for a wide range of neurodegenerative diseases," said Zhang. "You can generate neurons for specific conditions like amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease), Parkinson's disease or, in the case of my particular research area, eye-specific neurons that are lost in macular degeneration, retinitis pigmentosa or glaucoma."

The new process promises to have broad applications in stem cell research. The same method can be used to push induce pluripotent stem cells (stem cells artificially derived from adult, differentiated mature cells) to become neural stem cells, Zhang said. "And in principle, by altering the combination of small molecules, you may be able to create other types of stem cells capable of becoming heart, pancreas, or muscle cells, to name a few."

The next step, according to Zhang, is to use these stem cells to treat different types of neurodegenerative diseases, such as macular degeneration or glaucoma in animal models.

Funding for this research came, in part, from grants from National Institutes of Health Director's Transformative R01 Program, the National Institute of Child Health and Development, the National Heart, Lung, and Blood Institute, the National Eye Institute, the National Institute of Mental Health, the California Institute for Regenerative Medicine, a VA Merit Award, the Macula Vision Research Foundation, Research to Prevent Blindness, a Burroughs Wellcome Fund Clinical Scientist Award in Translational Research and the Richard and Carol Hertzberg Fund.

Co-authors of the study include Wenlin Li, Yu Zhang, Wanguo Wei, Rajesh Ambasudhan, Tongxiang Lin, Janghwan Kim, Department of Chemistry, The Scripps Research Institute; Woong Sun, Xiaolei Wang, UCSD Institute for Genomic Medicine and Shiley Eye Center, Department of Anatomy, Korea University College of Medicine, Seoul, Korea; Peng Xia, Maria Talantova, Stuart A. Lipton, Del E. Webb Center for Neuroscience, Aging and Stem Cell Research, Sanford-Burnham Medical Research Institute; Woon Ryoung Kim, Department of Anatomy, Korea University College of Medicine, Seoul, Korea.

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Stem Cells from Amniotic Fluid: Reprogrammed Amniotic Fluid Cells Can Generate All Types of Body Cells

Stem Cells from Amniotic Fluid: Reprogrammed Amniotic Fluid Cells Can Generate All Types of Body Cells

  10:06:00 AM    Science Lover

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Reprogrammed amniotic fluid cells can generate all types of body cells. High hopes rest on stem cells: one day, they may be used to treat many diseases. To date, embryos are the main source of these cells, but this raises ethical problems. Scientists at the Max Planck Institute for Molecular Genetics in Berlin have now managed to convert amniotic fluid cells into pluripotent stem cells. These amniotic fluid-derived iPS cells are hardly distinguishable from embryonic stem cells. However, they "remember" where they came from.

Top: Before their reprogramming into amniotic fluid iPS cells, 
human amniotic fluid cells are outwardly distinguishable from 
embryonic stem cells. Bottom left: Amniotic fluid iPS cells 
produce OCT4 (green), one of the most important marker 
proteins for embryonic stem cells. Bottom right: Starting from 
this embryonic stem cell phase, the amniotic fluid iPS cells can 
form hepatocyte-like cells and others. They produce the plasma
protein alpha-fetoprotein (red), which is abundant in fetal 
liver. (Credit: Max Planck Institute for Molecular Genetics)

The research appears in the online journal PLoS ONE, published by the Public Library of Science.

The special abilities of embryonic stem cells can today be used in multiple "grown-up" cells (e.g. skin and hair cells). This is done by reprogramming the cells and converting them to "induced pluripotent stem cells" (iPS cells). These then possess the typical properties of embryonic stem cells, meaning they can generate any of the cell types of the human body (pluripotency), and they can multiply endlessly.

Stem cells with memory
 
The scientists have shown that the amniotic fluid iPS cells can form different human cell types. They have also discovered that induced pluripotent stem cells can remember the original cell type from which they were generated. During cellular reprogramming, various genes that control the development of stem cells are apparently switched on or remain active. This confirms other current research results, which show that iPS cells derived from distinct tissues are prone to follow their pre-destined developmental path upon spontaneous differentiation. "We don't know just yet whether this donor-cell type memory will have an impact on possible medical treatment, or which type of somatic cell-derived iPS cell will be most suitable for treatment," cautions Katharina Wolfrum of the Max Planck Institute for Molecular Genetics.

Amniotic fluid cells have a number of advantages over other cell types. For one thing, amniotic fluid cells are routinely harvested in antenatal examinations to enable the early detection of disease. In most cases, more cells are obtained than are actually needed. In addition, the amniotic fluid mixture contains different types of cells from the unborn child, including stem-cell-like cells. As they are not very old, they have fewer environmentally-induced mutations, making them genetically more stable. "This may mean that it is possible to reprogram these amniotic fluid cells faster and more easily than other cell types, making amniotic fluid-derived iPS cells an interesting complement to embryonic stem cells," explains James Adjaye of the Max Planck Institute in Berlin.

Moreover, amniotic fluid cells could be extracted for cellular reprogramming before the birth of a child and be prepared for their intended use while the pregnancy is still ongoing. "This would make it possible to test which drugs work for a baby and whether they are tolerated, before that baby is born. Moreover, in the future, sick newborns can be treated with cells from their own body," says Adjaye.

Admin's Note: This article is not intended to provide medical advice, diagnosis or treatment.

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A New Way to Make Stem Cells Using RNA instead of DNA could avoid the health risks--and the political pitfalls--of stem-cell treatments.

A New Way to Make Stem Cells Using RNA instead of DNA could avoid the health risks--and the political pitfalls--of stem-cell treatments.

  1:27:00 AM    Science Lover

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A Harvard researcher has developed a way to make pluripotent stem cells that solves several of the major impediments to using them to treat human diseases.

New cell: This microscope image shows neurons
(colored green) created from pluripotent stem
cells using modified RNA.
Credit: Phil Manos, Cell Press

Derrick Rossi, an assistant professor at Harvard Medical School, created pluripotent stem cells--which can turn into virtually any other type of cell in the body--from non-stem cells without using viruses to tinker with a cell's genome, as conventional methods do. This means that Rossi's method could be substantially safer for treating disease. The work is published today in the journal Cell Stem Cell.

"Rossi has figured out how to turn a skin cell into a stem cell without genetic modifications, and to do it efficiently," said Doug Melton, codirector of the Harvard Stem Cell Institute, where Rossi is a principal faculty member, at a press conference.

Rossi's innovation, which has not yet been tested in people, was to use messenger RNA instead of DNA to produce the four proteins needed to reprogram the cell. He has started a company called ModeRNA to commercialize this use of messenger RNA. He said the approach may also have potential in gene therapy, which also relies on viruses to deliver treatment, but he declined to talk further about the company or possible gene therapy applications because the work is at such an early stage.

Improving the usability of man-made stem cells is key to helping patients and ending the political morass that has slowed stem-cell research. On Tuesday, a U.S. federal appeals court allowed federal funding of embryonic stem-cell research to continue while a legal case against such funding proceeds.

The human embryonic stem cells used in research were mostly derived from embryonic tissue grown a decade ago. These are the most versatile cells in the body, and the gold standard by which man-made cells are judged.

Four years ago, Japanese researcher Shinya Yamanaka showed that regular cells could be turned into embryonic-like stem cells--called induced pluripotent stem (iPS) cells--through the introduction of four specific proteins. Theoretically, this meant that doctors could take skin cells from a sick or disabled person, transform them into stem cells, and then into a specialized cell to treat them--an insulin-producing islet cell for someone with diabetes or a nerve cell for someone who is paralyzed, for instance. Using iPS cells avoids the need to destroy embryos and, because they can be derived from the patient's own cells, means less risk of rejection.

But only one in 1,000 or one in 10,000 skin cells could be transformed into a stem cell using Yamanaka's method. It also changes a cell's genes in ways that might trigger cancer or other problems.

Rossi 's idea was to produce Yamanaka's four proteins in a different way. Instead of using the DNA that holds the instructions for making proteins, he wanted to use RNA, which carries those instructions to the place in a cell where proteins are made.

His first several attempts were miserable failures. When he tried to change the messages the RNA carried, he triggered a serious immune response and most of the cells shut down or self-destructed. Rossi then tried modifying the RNA chemically and eventually figured out a way to allow his changes to escape immune detection while delivering the message. "This was key to our success," said Rossi, who is also a researcher at Children's Hospital Boston. "We could encode RNA for any protein we wanted to express and insert it into a cell."

Rossi said it was a happy coincidence that using RNA instead of changing the DNA was as much as 100-fold more efficient. He said the effect was possibly because the process more closely reflects how cells themselves transform.

Rossi successfully differentiated his stem cells into muscle cells using RNA, a process that may offer promise in gene therapy and other treatments. His method does not alter the cell's underlying genome, though Rossi admits that he does not yet understand what it does to the cell's epigenome, which controls expression of genes.

Rossi said that his cells, which he's named RiPS, for "RNA induced Pluripotent Stem" cells, are more like embryonic stem cells than traditional iPS cells because they have not been genetically altered.

Melton said the Harvard Stem Cell Institute, which includes several hundred stem-cell researchers from across Harvard University and its affiliated hospitals, will now be making its standard iPS cells with Rossi's method.

In a prepared statement, Yamanaka, now at the University of California, San Francisco, said Rossi's approach to generating stem cells seems promising, and he would like to have someone in his lab try it.

"The quality of the induced pluripotent stem cells generated by this method should be carefully examined because their characteristics vary depending on the induction methods and the origins of the resulting cells," he said. "The standard method to generate iPSCs for clinical applications has yet to be established. I think this method has the potential for it."

Jacob Hanna, a postdoctoral fellow at the Whitehead Institute for Biomedical Research in Cambridge, said he's also eager to begin working with the cells.

"I think it's a very exciting paper with a very promising method," said Hanna, who was not involved in the research. When asked if he was jealous that Rossi had developed the method first, Hanna said, "Yes, of course! It's a very nice paper," quickly adding, "Jealous in a very positive and supporting way."

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Better Way to Grow Stem Cells Developed

Better Way to Grow Stem Cells Developed

  10:59:00 PM    Science Lover

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Human pluripotent stem cells, which can become any other kind of body cell, hold great potential to treat a wide range of ailments, including Parkinson's disease, multiple sclerosis and spinal cord injuries. However, scientists who work with such cells have had trouble growing large enough quantities to perform experiments -- in particular, to be used in human studies. Furthermore, most materials now used to grow human stem cells include cells or proteins that come from mice embryos, which help stimulate stem-cell growth but would likely cause an immune reaction if injected into a human patient.

This image shows human embryonic stem cells grown on a synthetic surface developed by MIT researchers. The cells at top (blue) are stained to reveal their nuclei, while the cells in the middle and bottom are stained for proteins that are known to be present when cells are pluripotent. Green cells are stained for Oct4 (using green fluorescent protein) and red cells are stained for SSEA-4. (Credit: Ying Mei, Krishanu Saha, Robert Langer, Rudolf Jaenisch, and Daniel G. Anderson)

To overcome those issues, MIT chemical engineers, materials scientists and biologists have devised a synthetic surface that includes no foreign animal material and allows stem cells to stay alive and continue reproducing themselves for at least three months. It's also the first synthetic material that allows single cells to form colonies of identical cells, which is necessary to identify cells with desired traits and has been difficult to achieve with existing materials.

The research team, led by Professors Robert Langer, Rudolf Jaenisch and Daniel G. Anderson, describes the new material in the Aug. 22 issue of Nature Materials. First authors of the paper are postdoctoral associates Ying Mei and Krishanu Saha.

Human stem cells can come from two sources -- embryonic cells or body cells that have been reprogrammed to an immature state. That state, known as pluripotency, allows the cells to develop into any kind of specialized body cells.

It also allows the possibility of treating nearly any kind of disease that involves injuries to cells. Scientists could grow new neurons for patients with spinal cord injuries, for example, or new insulin-producing cells for people with type 1 diabetes.

To engineer such treatments, scientists would need to be able to grow stem cells in the lab for an extended period of time, manipulate their genes, and grow colonies of identical cells after they have been genetically modified. Current growth surfaces, consisting of a plastic dish coated with a layer of gelatin and then a layer of mouse cells or proteins, are notoriously inefficient, says Saha, who works in Jaenisch's lab at the Whitehead Institute for Biomedical Research.

"For therapeutics, you need millions and millions of cells," says Saha. "If we can make it easier for the cells to divide and grow, that will really help to get the number of cells you need to do all of the disease studies that people are excited about."

Previous studies had suggested that several chemical and physical properties of surfaces -- including roughness, stiffness and affinity for water -- might play a role in stem-cell growth. The researchers created about 500 polymers (long chains of repeating molecules) that varied in those traits, grew stem cells on them and analyzed each polymer's performance. After correlating surface characteristics with performance, they found that there was an optimal range of surface hydrophobicity (water-repelling behavior), but varying roughness and stiffness did not have much effect on cell growth.

They also adjusted the composition of the materials, including proteins embedded in the polymer. They found that the best polymers contained a high percentage of acrylates, a common ingredient in plastics, and were coated with a protein called vitronectin, which encourages cells to attach to surfaces.

Using their best-performing material, the researchers got stem cells (both embryonic and induced pluripotent) to continue growing and dividing for up to three months. They were also able to generate large quantities of cells -- in the millions.

The MIT researchers hope to refine their knowledge to help them build materials suited to other types of cells, says Anderson, from the MIT Department of Chemical Engineering, the Harvard-MIT Division of Health Sciences and Technology, and the David H. Koch Institute for Integrative Cancer Research. "We want to better understand the interactions between the cell, the surface and the proteins, and define more clearly what it takes to get the cells to grow," he says.

Other MIT authors of the paper are Said Bogatyrev, Z. Ilke Kalcioglu, Maisam Mitalipova, Neena Pyzocha, Fredrick Rojas and Krystyn Van Vliet. Jing Yang, Andrew Hook, Martyn Davies and Morgan Alexander of the University of Nottingham (United Kingdom) and Seung-Woo Cho of Yonsei University (Korea) are also authors of the paper.

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Toward Deafness Cure: Inner-Ear Cells Created

Toward Deafness Cure: Inner-Ear Cells Created

  9:47:00 PM    Science Lover

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Deep inside the ear, specialized cells called hair cells detect vibrations in the air and translate them into sound. Ten years ago, Stefan Heller, PhD, professor of otolaryngology at the Stanford University School of Medicine, came up with the idea that if you could create these cells in the laboratory from stem cells, it would go a long way toward helping scientists understand the molecular basis of hearing in order to develop better treatments for deafness.

Section through the organ of corti, 
showing inner and outer hair cells. 
(Credit: Courtesy of Wikimedia Commons)

After years of lab work, researchers in Heller's lab will report in the May 14 issue of Cell that they have found a way to develop mouse cells that look and act just like the animal's inner-ear hair cells -- the linchpin to our sense of hearing and balance -- in a petri dish.

If they can further perfect the recipe to generate hair cells in the millions, it could lead to significant scientific and clinical advances along the path to curing deafness in the future, they said.

"This gives us real hope that there might be some kind of therapy for regenerating hair cells," said David Corey, PhD, professor of neurobiology at Harvard University who was not involved in the study. "It could take a decade or more, but it's a possibility."

Using both embryonic stem cells from mice as well as reprogrammed mouse fibroblasts (a type of relatively undifferentiated cell found in many parts of the body), the researchers present a step-by-step guide on how to coax these cells into the sensory cells that normally reside in the inner ear.

"We knew it was really working when we saw them in the electron microscope," Heller said. "They really looked like they were more or less taken out of the ear."

Humans are born with 30,000 cochlear and vestibular hair cells per ear. (By contrast, one retina harbors about 120 million photoreceptors.) When a significant number of these cells are lost or damaged, hearing loss occurs. The major reason for hearing loss and certain balance disorders is that -- unlike other species such as birds -- humans and other mammals are unable to spontaneously regenerate these hearing cells.

As the population has aged and noise pollution has grown more severe, health experts now estimate that one in three adults over the age of 65 has developed a handicapping hearing loss due to the destruction of these limited number of hair cells.

One of the roadblocks to understanding the molecular basis of hearing is the paucity of hair cells available for study, Heller said. While researchers will ultimately need human hair cells, the mouse version is a good model for the initial phases of experimentation, he said. In addition to using mouse embryonic stem cells, the researchers used fibroblasts that had been reprogrammed to behave like stem cells: These are known as induced pluripotent stem cells, or iPS cells.

"Our study offers a protocol to generate millions of functional hair cells from a renewable source," Heller said. "We can now generate these cells and don't have to go through dozens of mice for a single experiment. This allows us to do molecular studies with much higher efficiency."

The study details how the researchers succeeded in coaxing the mouse embryonic stem cells and the iPS cells through different phases of development that occur in the womb. According to lead author Kazuo Oshima, MD, PhD, a research instructor at Stanford who works in Heller's lab, they started by turning the stem and iPS cells into the type of cells that form a young embryo's ectoderm -- the embryo's outer layer of cells that eventually differentiate into many tissues and structures, such as skin and nerve cells. Next they used specific growth factors to transform them into "otic-progenitor" cells (otic means ear). And after that, they varied the chemical soup in the dish, so that the cells clustered in a manner similar to hair cells and developed stereociliary bundles, which are also characteristic of hair cells.

"We looked at how the ear develops in an embryo, at the developmental steps, and mimicked these steps in a culture dish," Heller said.

Hair cells in the inner ear contain tiny clumps of hair-like projections, known as stereocilia. Sound vibrations cause the stereocilia to bend slightly, causing mechanical vibrations that are then converted into an electrochemical signal that the brain interprets as sound.

The cells in the petri dish, under close examination, had this same structure.

"These cells have a very intriguing structure," Heller said. "They look like they have hair tufts of stereocilia."

More importantly, further study showed that the cells also responded to mechanical stimulation by producing currents just like hair cells. Using a probe, researchers stimulated the bundles and recorded the currents that were evoked. Co-author Anthony Ricci, PhD, associate professor of otolaryngology, was responsible for this step of the work.

Heller, a leader in stem-cell based research on the inner ear, has recently been focused on two paths for possible cures for deafness: drug therapy -- which could be as simple as an application of ear drops -- and stem cell transplantation into the inner ear.

Both paths could be further advanced by the ability to develop hair-cell-like cells, he said. "We could now test thousands of drugs in a culture dish," he explained. "It is impossible to achieve such a scale in animals. Within a decade or so we could reap the benefits of this type of screening."

The lab's research into the regeneration of hair cells for transplantation into the inner ear to cure deafness will also continue.

"We made hair-cell-like cells in a petri dish," said Oshima. "This is an important step toward development of future therapies."

The study was funded by grants from the National Institute of Health, the California Institute for Regenerative Medicine and by a Neuroscience of Brain Disorders Award from the McKnight Endowment Fund for Neuroscience.

Other Stanford co-authors include postdoctoral scholars Kunyoo Shin, PhD; Mark Diensthuber, MD; and Anthony Peng, PhD.

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New Nerve Cells -- Even in Old Age: Researchers Find Different Types of Stem Cells in the Brains of Mature and Old Mice

New Nerve Cells -- Even in Old Age: Researchers Find Different Types of Stem Cells in the Brains of Mature and Old Mice

  10:25:00 AM    Science Lover

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After birth the brain loses many nerve cells and this continues throughout life -- most neurons are formed before birth, after which many excess neurons degenerate. However, there are some cells that are still capable of division in old age -- in the brains of mice, at least. According to scientists from the Max Planck Institute of Immunobiology in Freiburg, different types of neuronal stem cells exist that can create new neurons. While they divide continuously and create new neurons in young animals, a large proportion of the cells in older animals persist in a state of dormancy. However, the production of new cells can be reactivated, for example, through physical activity or epileptic seizures. What happens in mice could also be applicable to humans as neurons that are capable of dividing also occur in the human brain into adulthood.

Different types of stem cells in the brain of mature mice. 
(Credit: Verdon Taylor (from: Lugert et al., 
Cell Stem Cell, May 7th, 2010))

The research is published in the journal Cell Stem Cell.

You can't teach an old dog new tricks. The corresponding view that the brain loses learning and memory capacity with advancing age prevailed for a long time. However, neuronal stem cells exist in the hippocampus -- a region of the brain that plays a central role in learning and memory functions -- that can produce new nerve cells throughout life. It is known from tests on mice that the newly formed cells are integrated into the existing networks and play an important role in the learning capacity of animals. Nonetheless, the formation of new cells declines with age and the reasons for this were unknown up to now.

Together with colleagues from Dresden and Munich, the Freiburg researchers have now succeeded in explaining for the first time why fewer new neurons are formed in the adult mouse brain. They managed to identify different populations of neuronal stem cells, thereby demonstrating that the hippocampus has active and dormant or inactive neuronal stem cells. "In young mice, the stem cells divide four times more frequently than in older animals. However, the number of cells in older animals is only slightly lower. Therefore, neuronal stem cells do not disappear with age but are kept in reserve," explains Verdon Taylor from the Max Planck Institute of Immunobiology.

The precise factors that influence the reactivation of dormant stem cells are not yet clear. The cells can, however, be stimulated to divide again. The scientists observed more newborn hippocampal neurons in physically active mice than in their inactive counterparts. "Consequently, running promotes the formation of new neurons," says Verdon Taylor. Pathological brain activity, for example that which occurs during epileptic seizures, also triggers the division of the neuronal stem cells.

Horizontal and radial stem cells

The different stem cell populations are easy to distinguish under the microscope. The first group comprises cells which lie perpendicular to the surface of the hippocampus. Most of these radial stem cells are dormant. As opposed to this, over 80% of the cells in the group of horizontal stem cells -- cells whose orientation runs parallel to the hippocampus surface -- continuously form new cells; the remaining 20% are dormant but sporadically become activated. The activity of genes such as Notch, RBP-J and Sox2 is common to all of the cells.

Radial and horizontal stem cells differ not only in their arrangement, apparently they also react to different stimuli. When the animals are physically active, some radial stem cells abandon their dormant state and begin to divide, while this has little influence on the horizontal stem cells. The result is that more radial stem cells divide in active mice. The horizontal stem cells, in contrast, are also influenced by epileptic seizures.

It would appear that neuronal stem cells are not only found in the brains of mice. The presence of neurons that are formed over the course of life has also been demonstrated in the human hippocamus. Therefore, scientists suspect that different types of active and inactive stem cells also arise in the human brain. It is possible that inactive stem cells in humans can also be activated in a similar way to inactive stem cells in mice. "There are indicators that the excessive formation of new neurons plays a role in epilepsy. The use of neuronal brain stem cells in the treatment of brain injuries or degenerative diseases like Alzheimers may also be possible one day," hopes Verdon Taylor.

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