Category Archives: Stem Cell Videos

HOUSTON, Oct. 1, 2012 /PRNewswire/ --Celltex Therapeutics Corp. announced today that it has received a letter, dated Sept. 24, 2012, from the U.S. Food and Drug Administration. The letter stated the agency's opinion that the process Celltex uses to multiply adult stem cells is subject to FDA regulation as biological drug manufacturing. The issue is a key one as stem cell therapy for patient care outside of an academic institution is a new frontier, yet there are a variety of technologies being used throughout the United States, often creating complex legal and regulatory questions.

David Eller, CEO and President of Celltex, stated:

Celltex makes identical copies of an individual's own stem cells and therefore should not be subject to FDA regulation as drugs. However, the FDA said our process causes the cells to be considered biological drugs and thus is subject to those regulations. We respectfully but firmly disagree with the FDA and intend to contest the agency's opinion within its administrative procedures. We are considering all options as we work with the agency toward a resolution.

FDA's letter also repeats its earlier observations from an April inspection of Celltex's laboratory. While Celltex provided detailed responses in April, May, June, July and August, now FDA tells us it needs more information. We will answer FDA's questions in whatever detail the agency requests."

We will meet FDA's requirements, no matter how high the hurdles may be, to ensure access to this technology. Celltex remains fully committed to advance the most promising new field in human health in decades regenerative medicine. We also remain committed to doing so safely, and we will continue to comply with federal and state agency requirements.

As we work with the FDA, Celltex will continue to make advances on the frontier of regenerative medicine, and we expect to have several significant announcements in the coming weeks on these matters:

"Celltex is committed to developing the promise of regenerative medicine into a reality for doctors and their patients," Mr. Eller said. "We sponsor clinical trials to better understand the therapeutic impact and monitor the safety of adult stem cell therapy, and we are confident that our research will help implement effective treatments for patients suffering from a variety of medical conditions."

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Celltex To Initiate New Clinical Program As It Responds To FDA Letter

(Part III)

Primum Non NocerePrimarily, do no harm. This is the principal dictum of Dr. Samuel D. Bernal, MD, PHP, JD, MBA.

Board-certified and diplomate of the American Board of International Medicine and a fellow of Harvard Medical School, this doctor of chemistry, oncology and human biochemistry, health and regulatory law (specifically medical malpractice) holds offices in Los Angeles, Prague and Manila.

His name is synonymous with personalized molecular medicine, the heart of which evolves around stem cells.

Dr. Bernal pioneered in the analysis of the electrical energy of the cell in the living state. And thus, in his regimen, which includes 300 mixes of vitamins, minerals, proteins and essential fats, the electrical production of the mitochondria is ensured.

Here is the result of our two-hour candid discussion about rejuvenation, health and beauty. While the 120-minute immersion cant give a complete understanding of the vast and complex world of the human body, it was nevertheless enough time to begin to grasp the basic truththat all the power of life rests within us all.

Q: What exactly are stem cells?

Stem cells (SC) are merely a small component of what we call regenerative medicine. And they have the ability to heal and repair the body back to a good health.

Q: Isnt it as simple as injecting stem cells into the human body?

Definitely not. There is the matter of molecular biology. No two individuals are alike. And this makes the idea of injecting a commercially-prepared stem cell solution into your body questionable and even dangerous.

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An expert talks about stem cells

GRAND FORKS The goal of a Grand Forks start-up is to get customers to prepare for a future in which todays medical breakthroughs based on stem cells are commonplace.

You would ordinarily think this is science fiction, said Vin Singh, founder of Next Healthcare, based at UNDs Center for Innovation.

Singh is referring to developments in regenerative medicine in which researchers have used stem cells to re-grow lung, cornea and trachea cells and create other types of human tissue. These advances point to a future when replacing organs will become a common medical procedure.

And he wants people to act now.

Singhs business, which he has been building since 2009 and launched this past spring, is a cell bank, storing samples of clients skin, blood and bone marrow cells for future use when regenerative treatments are improved and widespread.

We know some of them are going to work, and were betting that youre going to be able to use some of your cells, Singh said. If and when those therapies come on line, you will have that healthy seed.

Betting on future

Singhs resume lists a number of companies in the biomedical field. But the basis of his new business is essentially storage, freezing samples of clients tissue that could be used by doctors to treat future health problems.

Clients doctors collect their tissue samples and send them to Next Healthcare in Grand Forks, where they are stored frozen. The company is based in UNDs REAC building, which provides biocontainment facilities. Next Healthcare also has a second storage facility in North Dakota at an undisclosed location, Singh said.

The key to therapies that Singhs company is betting on and wants prospective customers to bet on are advances within the past decade that have manipulated non-stem cells from skin or blood to mimic stem cells ability to grow into different types of tissues.

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Grand Forks firm stores human cells for future treatments

ALAMEDA, Calif.--(BUSINESS WIRE)--

BioTime, Inc. (NYSE MKT: BTX), an Alameda-based company engaged in research and development of innovative new products in the field of regenerative medicine utilizing stem cells and related technology, announced today that it has formed a new wholly owned subsidiary, BioTime Acquisition Corporation, to pursue opportunities and acquire assets and businesses in the fields of stem cells and regenerative medicine. Thomas Okarma, PhD, MD, will serve as the Chief Executive Officer and as a member of the board of directors of BioTimes new subsidiary. Dr. Okarma is the former President and Chief Executive Officer of Geron Corporation and served on that companys board of directors.

Since 2010, BioTime has expanded the scope of its business through strategic acquisitions and has been continually exploring other acquisition opportunities in its fields of interest. BioTimes strategic acquisitions include:

Global advances on multiple fronts of stem cell biology have established the foundation for an integrative business approach to consolidate and translate these discoveries into products that may revolutionize clinical medicine, said Thomas Okarma, the new companys CEO. Living cell therapies can now be scalably manufactured, efficiently distributed to points of care, and tested in controlled clinical trials.The goal of regenerative medicine is to go beyond the reach of pills and scalpels to achieve a new level of healing that may, after a single administration of therapeutic cells, permanently restore function to tissues and organs damaged by chronic disease or injury. BioTime Acquisition Corporation intends to build its business by identifying, consolidating, and commercially developing the best available cell therapy technologies to realize the potential of regenerative medicine. Ultimately, the goal is to bring these new therapies to the many millions of patients who need them.

The breadth of Dr. Okarmas experience in the field of cell-based therapeutics is simply spectacular, said Michael D. West, PhD, BioTimes Chief Executive Officer. We look forward to working together with him to translate these new scientific advances into commercial products for the large and growing markets driven by age-related degenerative diseases.

Dr. Okarma has had a distinguished career as a physician and an innovator and executive in the biotechnology industry. Dr. Okarma served as Gerons President, Chief Executive Officer, and as a member of its board of directors from July 1999 until February 2011, after having previously served as that companys Vice President of Research and Development and Vice President of Cell Therapies. In 1985, Dr. Okarma founded Applied Immune Sciences, Inc. (AIS) and served initially as its Vice President of Research and Development and subsequently as Chairman and Chief Executive Officer and as a director until that company was acquired by Rhone-Poulenc Rorer in 1995. After that acquisition, Dr. Okarma served as a Senior Vice President at Rhone-Poulenc Rorer until December 1996. From 1980 to 1992, Dr. Okarma was a member of the faculty of the Department of Medicine at Stanford University School of Medicine. Dr. Okarma holds an AB from Dartmouth College, an MD and PhD from Stanford University, and is a graduate of the Executive Education program of the Stanford Graduate School of Business.

About BioTime, Inc.

BioTime, headquartered in Alameda, California, is a biotechnology company focused on regenerative medicine and blood plasma volume expanders. Its broad platform of stem cell technologies is enhanced through subsidiaries focused on specific fields of application. BioTime develops and markets research products in the fields of stem cells and regenerative medicine, including a wide array of proprietary ACTCellerate cell lines, HyStem hydrogels, culture media, and differentiation kits. BioTime is developing Renevia (formerly known as HyStem-Rx), a biocompatible, implantable hyaluronan and collagen-based matrix for cell delivery in human clinical applications. BioTime's therapeutic product development strategy is pursued through subsidiaries that focus on specific organ systems and related diseases for which there is a high unmet medical need. BioTime's majority owned subsidiary Cell Cure Neurosciences Ltd. is developing therapeutic products derived from stem cells for the treatment of retinal and neural degenerative diseases. BioTime's subsidiary OrthoCyte Corporation is developing therapeutic applications of stem cells to treat orthopedic diseases and injuries. Another subsidiary, OncoCyte Corporation, focuses on the diagnostic and therapeutic applications of stem cell technology in cancer, including the diagnostic product PanC-Dx currently being developed for the detection of cancer in blood samples. ReCyte Therapeutics, Inc. is developing applications of BioTime's proprietary induced pluripotent stem cell technology to reverse the developmental aging of human cells to treat cardiovascular and blood cell diseases. BioTime's subsidiary LifeMap Sciences, Inc. markets GeneCards, the leading human gene database, and is developing an integrated database suite to complement GeneCards that will also include the LifeMap database of embryonic development, stem cell research and regenerative medicine, and MalaCards, the human disease database. LifeMap will also market BioTime research products. BioTime's lead product, Hextend, is a blood plasma volume expander manufactured and distributed in the U.S. by Hospira, Inc. and in South Korea by CJ CheilJedang Corporation under exclusive licensing agreements. Additional information about BioTime can be found on the web at http://www.biotimeinc.com.

Forward-Looking Statements

Statements pertaining to future financial and/or operating results, future growth in research, technology, clinical development, and potential opportunities for BioTime and its subsidiaries, along with other statements about the future expectations, beliefs, goals, plans, or prospects expressed by management constitute forward-looking statements. Any statements that are not historical fact (including, but not limited to statements that contain words such as "will," "believes," "plans," "anticipates," "expects," "estimates") should also be considered to be forward-looking statements. Forward-looking statements involve risks and uncertainties, including, without limitation, risks inherent in the development and/or commercialization of potential products, uncertainty in the ability to identify and complete potential acquisitions, the ability to realize anticipated benefits of and achieve expected financial performance following completed acquisitions, the results of clinical trials or regulatory approvals, need and ability to obtain future capital, and maintenance of intellectual property rights. Actual results may differ materially from the results anticipated in these forward-looking statements and as such should be evaluated together with the many uncertainties that affect the business of BioTime and its subsidiaries, particularly those mentioned in the cautionary statements found in BioTime's Securities and Exchange Commission filings. BioTime disclaims any intent or obligation to update these forward-looking statements.

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BioTime Forms BioTime Acquisition Corporation

Featured Article Academic Journal Main Category: Stem Cell Research Also Included In: Biology / Biochemistry Article Date: 28 Sep 2012 - 1:00 PDT

Current ratings for: Purging Stem Cells To Make Therapy Safer

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The study appears in a 27 September issue of the journal Stem Cells Translational Medicine.

iPS cells have properties similar to embryonic stem cells, which are "master cells" with an unlimited capacity to differentiate into any type of tissue in the body, such as brain, lung, skin, heart, and liver. Thus their potential in regenerative medicine, where damaged or diseased tissue can be repaired or replaced by growing new tissue, is huge, as senior author Timothy Nelson explains in a press release:

"Pluripotent stem cells show great promise in the field of regenerative medicine; however, the risk of uncontrolled cell growth will continue to prevent their use as a therapeutic treatment."

Nelson is Assistant Professor of Medicine and Pharmacology and works in the General Internal Medicine department and the Transplant Center at the Mayo.

The idea of using iPS cells is for doctors to be able to take some adult tissue, for example skin cells, from the patient who needs the treatment, and then turn the cells from that tissue into iPS cells.

Then, those iPS cells are coaxed to turn into the target type of cell, for instance lung cells. As a result of the coaxing the iPS cells turn into (differentiate) the target tissue type.

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Purging Stem Cells To Make Therapy Safer

MARLBOROUGH, Mass.--(BUSINESS WIRE)--

Advanced Cell Technology, Inc. (ACT; OTCBB: ACTC), a leader in the field of regenerative medicine, announced today that its chief scientific officer, Robert Lanza, M.D. and Anthony Atala, M.D., W.H. Boyce Professor and Director of the Wake Forest Institute for Regenerative Medicine, have released the second edition of Handbook of Stem Cells (Academic Press/Elsevier), the widely-recognized definitive resource in the field of stem cells. It includes a Forward by Professor Sir Martin Evans, Ph.D., FRS, co-winner of the Nobel Prize for Physiology or Medicine in 2007. Sir Martin is credited with discovering embryonic stem cells and is considered one of the chief architects of the field of stem cell research. The two-volume set also includes contributions from dozens of stem cell pioneers, including James Thomson, Shinya Yamanaka, Doug Melton, Janet Rossant, and Robert Langer (a member of ACTs board of directors), among others, as well as patient advocate Mary Tyler Moore.

Handbook of Stem Cells, Second Edition follows a very successful edition published in 2004. The first edition was the first comprehensive body of work dedicated entirely to the stem cell field. The two-volume set quickly became the most relevant textbook in the stem cell arena. Now, several years later, major advances have occurred, with entirely new classes of stem cells being described. The description of induced pluripotent cells in the last few years brought many more avenues of research and discovery. In 2012, the first paper reporting results of two patients treated with human embryonic stem cells was published by ACT and its collaborators. It might seem that we have waited too long to finally see pluripotent stem cells in the clinic. However, this has been accomplished with incredible speed when it is considered that hESCs were first isolated just 14 years ago. Handbook of Stem Cells integrates this exciting area, combining in two volumes the requisites for a general understanding of both adult and embryonic stem cells. Organized in two volumes, Pluripotent Stem Cells and Adult & Fetal Stem Cells, this work contains contributions from the world's experts in stem cell research to provide a description of the tools, methods, and experimental protocols needed to study and characterize stem cells and progenitor populations as well as a the latest information of what is known about each specific organ system.

The Handbook of Stem Cells, edited by Robert Lanza and colleagues, is an ambitious new text that achieves extraordinary completeness and inclusiveness, wrote Steve Goldman of University of Rochester Medical Center in NATURE CELL BIOLOGY about the first edition. [...] the editors have succeeded in putting together a reference that is broad enough in scope, but sufficiently detailed and rigorous, to be of real interest to both new and seasoned investigators in the field [...] In providing this treatise, which covers the history, biology, methods and applications of stem cells, the editors and authors have succeeded in establishing a conceptual framework and a common language for the field. In so doing, they have ensured that this two-volume set will serve as a benchmark reference in stem cell biology for years to come.

Writing about the first edition in the Times Higher Education Supplement, Ian Wilmut added, These books make an invaluable contribution to the education of researchers and clinicians both of the present day and of the future. They should be available in libraries of all biology and medical schools as well as those of companies and research institutions.

About Advanced Cell Technology, Inc.

Advanced Cell Technology, Inc., is a biotechnology company applying cellular technology in the field of regenerative medicine. For more information, visit http://www.advancedcell.com.

Forward-Looking Statements

Statements in this news release regarding future financial and operating results, future growth in research and development programs, potential applications of our technology, opportunities for the company and any other statements about the future expectations, beliefs, goals, plans, or prospects expressed by management constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Any statements that are not statements of historical fact (including statements containing the words will, believes, plans, anticipates, expects, estimates, and similar expressions) should also be considered to be forward-looking statements. There are a number of important factors that could cause actual results or events to differ materially from those indicated by such forward-looking statements, including: limited operating history, need for future capital, risks inherent in the development and commercialization of potential products, protection of our intellectual property, and economic conditions generally. Additional information on potential factors that could affect our results and other risks and uncertainties are detailed from time to time in the companys periodic reports, including the report on Form 10-K for the year ended December 31, 2011. Forward-looking statements are based on the beliefs, opinions, and expectations of the companys management at the time they are made, and the company does not assume any obligation to update its forward-looking statements if those beliefs, opinions, expectations, or other circumstances should change. Forward-looking statements are based on the beliefs, opinions, and expectations of the companys management at the time they are made, and the company does not assume any obligation to update its forward-looking statements if those beliefs, opinions, expectations, or other circumstances should change. There can be no assurance that the Companys clinical trials will be successful.

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New Edition of Definitive (Two-Volume) Resource in Stem Cells Released Today

Public release date: 28-Sep-2012 [ | E-mail | Share ]

Contact: Charles Casey charles.casey@ucdmc.ucdavis.edu 916-734-9048 University of California - Davis Health System

(SACRAMENTO, Calif.) UC Davis investigators have found new evidence that a promising type of stem cell now being considered for a variety of disease therapies is very similar to the type of cells that give rise to cancer. The findings suggest that although the cells -- known as induced pluripotent stem cells (iPSCs) -- show substantial promise as a source of replacement cells and tissues to treat injuries, disease and chronic conditions, scientists and physicians must move cautiously with any clinical use because iPSCs could also cause malignant cancer.

The article, "Induced pluripotency and oncogenic transformation are related processes," is now online in the journal, Stem Cells and Development.

"This is the first study that describes the specific molecular pathways that iPSCs and cancer cells share from a direct comparison" said Paul Knoepfler, associate professor of cell biology and human anatomy, and principal investigator of the study. "It means that much more study is required before iPSCs can be used clinically. However, our study adds to a growing knowledge base that not only will help make stem cell therapies safer, but also provide us with new understandings about the cancer-causing process and more effective ways to fight the disease."

Since 2007, cell biologists have been able to induce specialized, differentiated cells (such as those obtained from the skin or muscle of a human adult) to become iPSCs. Like embryonic stem cells, iPSCs are a type of stem cell that is able to become any cell type. This "pluripotent" capability means that iPSCs have the potential of being used in treatments for a variety of human diseases, a fundamentally new type of clinical care known as regenerative medicine.

iPSCs are considered particularly important because their production avoids the controversy that surrounds embryonic stem cells. In addition, iPSCs can be taken from a patient's own skin and induced to produce other needed tissues, thereby evading the possibility of immunologic rejection that arises when transplanting cells from a donor to a recipient. In contrast to therapies based on ES cells, iPSCs would eliminate the need for patients to take immunosuppressive drugs.

Earlier research indicated that both ES cells and iPSCs pose some health risks. Increasing evidence suggests that pluripotency may be related to rapid cellular growth, a characteristic of cancer. iPSCs, as well as embryonic stem cells, are well known by scientists to have the propensity to cause teratomas, an unusual type of benign tumor that consists of many different cell types. The new UC Davis study demonstrates for the first time that iPSCs -- as well as ES cells -- share significant similarities to malignant cancer cells.

The investigators compared iPSCs to a form of malignant cancer known as oncogenic foci that are also produced in laboratories; these cell types are used by medical researchers to create models of cancer, particularly sarcoma. Specifically, the scientists contrasted the different cells' transcriptomes, comprised of the RNA molecules or "transcripts." Unlike DNA analysis, which reflects a cell's entire genetic code whether or not the genes are active, transcriptomes reflect only the genes that are actively expressed at a given time and therefore provide a picture of actual cellular activity.

From this transcriptome analysis, the investigators found that the iPSCs and malignant sarcoma cancer cells are unexpectedly similar in several respects. Genes that were not expressed in iPSCs were also not expressed in the cancer-generating cells, including many that have properties that guide a cell to normally differentiate in certain directions. Both cell types also exhibited evidence of similar metabolic activities, another indication that they are related cell types.

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Researchers find multiple similarities between cancer cells and induced pluripotent stem cells

ScienceDaily (Sep. 28, 2012) UC Davis investigators have found new evidence that a promising type of stem cell now being considered for a variety of disease therapies is very similar to the type of cells that give rise to cancer. The findings suggest that although the cells -- known as induced pluripotent stem cells (iPSCs) -- show substantial promise as a source of replacement cells and tissues to treat injuries, disease and chronic conditions, scientists and physicians must move cautiously with any clinical use because iPSCs could also cause malignant cancer.

The article, "Induced pluripotency and oncogenic transformation are related processes," is now online in the journal, Stem Cells and Development.

"This is the first study that describes the specific molecular pathways that iPSCs and cancer cells share from a direct comparison" said Paul Knoepfler, associate professor of cell biology and human anatomy, and principal investigator of the study. "It means that much more study is required before iPSCs can be used clinically. However, our study adds to a growing knowledge base that not only will help make stem cell therapies safer, but also provide us with new understandings about the cancer-causing process and more effective ways to fight the disease."

Since 2007, cell biologists have been able to induce specialized, differentiated cells (such as those obtained from the skin or muscle of a human adult) to become iPSCs. Like embryonic stem cells, iPSCs are a type of stem cell that is able to become any cell type. This "pluripotent" capability means that iPSCs have the potential of being used in treatments for a variety of human diseases, a fundamentally new type of clinical care known as regenerative medicine.

iPSCs are considered particularly important because their production avoids the controversy that surrounds embryonic stem cells. In addition, iPSCs can be taken from a patient's own skin and induced to produce other needed tissues, thereby evading the possibility of immunologic rejection that arises when transplanting cells from a donor to a recipient. In contrast to therapies based on ES cells, iPSCs would eliminate the need for patients to take immunosuppressive drugs.

Earlier research indicated that both ES cells and iPSCs pose some health risks. Increasing evidence suggests that pluripotency may be related to rapid cellular growth, a characteristic of cancer. iPSCs, as well as embryonic stem cells, are well known by scientists to have the propensity to cause teratomas, an unusual type of benign tumor that consists of many different cell types. The new UC Davis study demonstrates for the first time that iPSCs -- as well as ES cells -- share significant similarities to malignant cancer cells.

The investigators compared iPSCs to a form of malignant cancer known as oncogenic foci that are also produced in laboratories; these cell types are used by medical researchers to create models of cancer, particularly sarcoma. Specifically, the scientists contrasted the different cells' transcriptomes, composed of the RNA molecules or "transcripts." Unlike DNA analysis, which reflects a cell's entire genetic code whether or not the genes are active, transcriptomes reflect only the genes that are actively expressed at a given time and therefore provide a picture of actual cellular activity.

From this transcriptome analysis, the investigators found that the iPSCs and malignant sarcoma cancer cells are unexpectedly similar in several respects. Genes that were not expressed in iPSCs were also not expressed in the cancer-generating cells, including many that have properties that guide a cell to normally differentiate in certain directions. Both cell types also exhibited evidence of similar metabolic activities, another indication that they are related cell types.

"We were surprised how similar iPSCS were to cancer-generating cells," said Knoepfler. "Our findings indicate that the search for therapeutic applications of iPSCs must proceed with considerable caution if we are to do our best to promote patient safety."

Knoepfler noted, for example, that future experimental therapies using iPSCs for human transplants would most often not involve implanting iPSCs directly into a patient. Instead, iPSCs would be used to create differentiated cells -- or tissues -- in the laboratory, which could then be transplanted into a patient. This approach avoids implanting the actual undifferentiated iPSCS, and reduces the risk of tumor development as a side effect. However, Knoepfler noted that even trace amounts of residual iPSCs could cause cancer in patients, a possibility supported by his team's latest research.

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Multiple similarities discovered between cancer cells and induced pluripotent stem cells

ScienceDaily (Sep. 27, 2012) A new regulator for heart formation has been discovered by studying how embryonic stem cells adjust the packaging of their DNA. This approach to finding genetic regulators, the scientists say, may have the power to provide insight into the development of any tissue in the body -- liver, brain, blood and so on.

A stem cell has the potential to become any type of cell. Once the choice is made, the cell and other stem cells committed to the same fate divide to form organ tissue.

A University of Washington-led research team was particularly interested in how stem cells turn into heart muscle cells to further research on repairing damaged hearts through tissue regeneration. The leaders of the project were Dr. Charles Murry, a cardiac pathologist and stem cell biologist; Dr. Randall Moon, who studies the control of embryonic development, and Dr. John Stamatoyannopoulos, who explores the operating systems of the human genome.

The paper's lead author is Dr. Sharon Paige, a UW MD-PhD student who completed her Ph.D. in Dr. Murry's lab.

The results are published in the Sept. 28 edition of Cell.

Paige, an aspiring pediatric cardiologist, said, "By identifying regulators of cardiac development, this work has the potential to lead to a better understanding of the causes of congenital heart disease, thereby paving the way for therapeutic advances."

Previously UW researchers had examined the signals that prod cells to grow into various kinds of heart tissue. In this case, the researchers entered a relatively unexplored area. They decided to look at the genetic controls behind the transformation of stem cells into heart tissue.

Because stem cells keep their DNA code under wraps until needed, the scientists examined how this packaging is altered over time to permit reading of portions of the code and thereby produce changes in the cell.

DNA is wound up into a structure called chromatin. "DNA can be packaged as tightly closed, neutral or activated," Murry explained. The tightly closed state, he said, is analogous to setting the brakes on a car.

Like a child who clams up when asked, "What will you be when you grow up?" stem cells are protective of the genes that will determine their future cell type, or what scientists call their cell fate.

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Dynamics of DNA packaging helps regulate formation of heart

ScienceDaily (Sep. 27, 2012) Working with mice, Johns Hopkins researchers have solved a key part of a muscle regeneration mystery plaguing scientists for years, adding strong support to the theory that muscle mass can be built without a complete, fully functional supply of muscle stem cells.

"This is good news for those with muscular dystrophy and other muscle wasting disorders that involve diminished stem cell function," says Se-Jin Lee, M.D., Ph.D., lead author of a report on the research in the August issue of the Proceedings of the National Academy of Sciences, and professor of molecular biology and genetics at the Johns Hopkins University School of Medicine.

Muscle stem cells, known as satellite cells, reside next to muscle fibers and are usually dormant in adult mammals, including humans. After exercise or injury, they are stimulated to divide and fuse, either with themselves or with nearby muscle fibers, to increase or replace muscle mass. In muscle wasting disorders, like muscular dystrophy, muscle degeneration initially activates satellite cells to regenerate lost tissue, but eventually the renewal cycle is exhausted and the balance tips in favor of degeneration, the researchers explain.

Muscle maintenance and growth under healthy, non-injury conditions have been more of a mystery, including the role of myostatin, a protein secreted from muscle cells to stop muscle growth. Blocking myostatin function in normal mice causes them to bulk up by 25 to 50 percent. What is not known is which cells receive and react to the myostatin signal. Current suspects include satellite cells and muscle cells themselves.

In this latest study, researchers used three approaches to figure out whether satellite cells are required for myostatin activity. They first looked at specially bred mice with severe defects in either satellite cell function or number. When they used drugs or genetic engineering to block myostatin function in both types of mice, muscle mass still increased significantly compared to that seen in mice with normal satellite cell function, suggesting that myostatin is able to act, at least partially, without full satellite cell function.

Second, the researchers guessed that if myostatin directly inhibits the growth of satellite cells, their numbers should increase in the absence of myostatin. The researchers marked the satellite cells with a permanent dye and then blocked myostatin activity with a drug. Mouse muscle mass increased significantly as expected, but the satellite cells did not increase in number, nor were they found fusing with muscle fibers at a higher rate. According to Lee, these results strongly suggest that myostatin does not suppress satellite cell proliferation.

Third, to further confirm their theory that myostatin acts primarily through muscle cells and not satellite cells, the team engineered mice with muscle cells lacking a protein receptor that binds to myostatin. If satellite cells harbor most of the myostatin receptors, removal of receptors in muscle cells should not alter myostatin activity, and should result in muscles of normal girth. Instead, what the researchers saw was a moderate, but statistically significant, increase in muscle mass. The evidence once again, they said, suggested that muscle cells are themselves important receivers of myostatin signals.

Lee notes that, since the results give no evidence that satellite cells are of primary importance to the myostatin pathway, even patients with low muscle mass due to compromised satellite cell function may be able to rebuild some of their muscle tone through drug therapy that blocks myostatin activity.

"Everybody loses muscle mass as they age, and the most popular explanation is that this occurs as a result of satellite cell loss. If you block the myostatin pathway, can you increase muscle mass, mobility and independence for our aging population?" asks Lee. "Our results in mice suggest that, indeed, this strategy may be a way to get around the satellite cell problem."

Authors on the paper include Se-Jin Lee, Thanh Huynh, Yun-Sil Lee and Suzanne Sebald from The Johns Hopkins University, Sarah Wilcox-Adelman of Boston Biomedical Research Institute, Naoki Iwamori and Martin Matzuk of Baylor College of Medicine, and Christoph Lepper and Chen-Ming Fan from the Carnegie Institution for Science.

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Key part of old mystery in generating muscle mass solved