Researchers map gene that regulates adult stem cell growth

Sur le même thème que "Researchers map gene that regulates adult stem cell growth"

Technique enables efficient gene splicing in human embryonic stem cells

A novel technique allows researchers to efficiently and precisely modify or introduce genes into the genomes of human embryonic stem cells (ESCs) and induced pluripotent stem (iPS) cells, according to Whitehead scientists. The method uses proteins called zinc finger nucleases and is described in the August 3 issue of Nature Biotechnology. For years, scientists have easily swapped genes in and out of mouse ESC or iPS cell genomes, but have had a notoriously difficult time disrupting or inserting genes into their human equivalents. “It’s not clear where this hurdle of genetic manipulation lies; it could be purely technical, but it could also be an inherent difference between human and mouse cells,” says Dirk Hockemeyer. [lien] [EN]

Researchers map out networks that determine cell fate

A two-step process appears to regulate cell fate decisions for many types of developing cells, according to researchers from the University of Chicago. This finding sheds light on a puzzling behavior. For some differentiating stem cells, the first step leads not to a final decision but to a new choice. In response to the initial chemical signal, these cells take on the genetic signatures of two different cell types. It often requires a second signal for them to commit to a single cellular identity. In the Aug. 25 2006 issue of Cell, the researchers, working with hematopoietic stem cells, which give rise to the many types of blood cells, show how “pioneer transcription factors” trigger the first step. [lien] [EN]

Researchers map out networks that determine cell fate

A two-step process appears to regulate cell fate decisions for many types of developing cells, according to researchers from the University of Chicago. This finding sheds light on a puzzling behavior. For some differentiating stem cells, the first step leads not to a final decision but to a new choice. In response to the initial chemical signal, these cells take on the genetic signatures of two different cell types. It often requires a second signal for them to commit to a single cellular identity. In the Aug. 25 2006 issue of Cell, the researchers, working with hematopoietic stem cells, which give rise to the many types of blood cells, show how “pioneer transcription factors” trigger the first step. [lien] [EN]

Researchers create genetically matched embryonic stem cells for transplantation

Researchers at Children’s Hospital Boston report a new and efficient strategy, using eggs alone, for creating mouse embryonic stem cells that can be transplanted without the risk of rejection because the cells are compatible with the recipient’s immune system. The findings are published online in the journal Science on December 14. Though done in mice, the work establishes the principle of using unfertilized eggs as a source of customized embryonic stem cells that are genetically matched to the egg donor at the genes that control recognition of cells by the immune system, making them potentially useful for transplantation therapies. There are several caveats, including the fact that only females could benefit from this technique. [lien] [EN]

Blood stem cell growth factor reverses memory decline in mice

A human growth factor that stimulates blood stem cells to proliferate in the bone marrow reverses memory impairment in mice genetically altered to develop Alzheimer’s disease, researchers at the University of South Florida and James A. Haley Hospital found. The granulocyte-colony stimulating factor (GCSF) significantly reduced levels of the brain-clogging protein beta amyloid deposited in excess in the brains of the Alzheimer’s mice, increased the production of new neurons and promoted nerve cell connections. [Plaques] Caption - Microglia (in green) attack the beta amyloid (red) deposited in the brain of a GCSF-treated Alzheimer's mouse. Credit: Photo courtesy of University of South Florida [lien] [EN]

Scientists find previously unknown receptors on adult stem cells

For many years, researchers believed that stem cells in the bone marrow spent most of their existence in a slumber-like state, unaware of — and unaffected by — the daily battles fought by the body's immune system. Not so. Scientists at the Oklahoma Medical Research Foundation have discovered that marrow stem cells — undifferentiated cells that eventually give rise to the blood cells that fight infection — possess receptors that recognize bacteria and viruses. When activated, these receptors kick the stem cells and immature blood cells into action, enlisting them to help fight whatever pathogen is attacking the body. The findings, which appear in the June issue of the journal Immunity, could have important implications for treating leukemias and autoimmune diseases such as lupus and rheumatoid arthritis. [lien] [EN]

Scientists identifies gene that regulates blood-forming fetal stem cells

In the rancorous public debate over federal research funding, stem cells are generally assigned to one of two categories: embryonic or adult. But that’s a false dichotomy and an oversimplification. A new University of Michigan study adds to mounting evidence that stem cells in the developing fetus are distinct from both embryonic and adult stem cells. In the last several years, stem cell researchers have realized that fetal stem cells comprise a separate class. They recognized, for example, that fetal blood-forming stem cells in umbilical cord blood behave differently than adult blood-forming stem cells after transplantation into patients. Now a U-M team led by Sean Morrison has identified the first known gene. [lien] [EN]

Researchers identify a critical growth factor that stimulates sperm stem cells to thrive

Researchers at the University of Pennsylvania School of Veterinary Medicine and Pennsylvania State University have identified for the first time a specific “niche factor” in the mouse testes called colony stimulating factor , Csf, that has a direct effect on sperm stem cell self-renewal. Moreover, the study shows that the origin of this growth factor is the Leydig cell — located in the testes and stimulated by the pituitary gland to supply testosterone — that secretes Csf1 and enhances self-renewal of the stem cells. The finding, based upon a decade of related research, shows that stem cells are influenced to increase divisions by this growth factor, which provides a powerful new model in the study of stem cells and shows they interact with their microenvironment called the “niche. [lien] [EN]

Master switches found for adult blood stem cells

Scientists have found a set of “master switches” that keep adult blood-forming stem cells in their primitive state. Unlocking the switches’ code may one day enable scientists to grow new blood cells for transplant into patients with cancer and other bone marrow disorders. The scientists located the control switches not at the gene level, but farther down the protein production line in more recently discovered forms of ribonucleic acid, or RNA. MicroRNA molecules, once thought to be cellular junk, are now known to switch off activity of the larger RNA strands which allow assembly of the proteins that let cells grow and function. “Stem cells are poised to make proteins essential for maturing into blood cells, but microRNAs keep them locked in their place. [lien] [EN]

Researchers transform stem cells found in human fat into smooth muscle cells

Researchers at UCLA today announced they have transformed adult stem cells taken from human adipose – or fat tissue – into smooth muscle cells, which help the normal function of a multitude of organs like the intestine, bladder and arteries. The study may help lead to the use of fat stem cells for smooth muscle tissue engineering and repair. Reported in the July 24 online edition of the Proceedings of the National Academy of Sciences, the study is one of the first to show that stem cells derived from adipose tissue can be changed to acquire the physical and biochemical characteristics as well as the functionality of smooth muscle cells. Smooth muscle cells are found within the human body in the walls of hollow organs like blood vessels. [lien] [EN]

Genes That Control Embryonic Stem Cell Fate Identified

Scientists have identified about two dozen genes that control embryonic stem cell fate. The genes may either prod or restrain stem cells from drifting into a kind of limbo, they suspect. The limbo lies between the embryonic stage and fully differentiated, or specialized, cells, such as bone, muscle or fat. By knowing the genes and proteins that control a cell’s progress toward the differentiated form, researchers may be able to accelerate the process — a potential boon for the use of stem cells in therapy or the study of some degenerative diseases, the scientists say. Their finding comes from the first large-scale search for genes crucial to embryonic stem cells. The research was carried out by a team at the University of California. [lien] [EN]

Stem Cells Restore Muscle In Mice With Muscular Dystrophy

Researchers at the Joslin Diabetes Center have demonstrated for the first time that transplanted muscle stem cells can both improve muscle function in animals with a form of muscular dystrophy and replenish the stem cell population for use in the repair of future muscle injuries. “I’m very excited about this,” said lead author Amy J. Wagers, Ph.D., Principal Investigator in the Joslin Section on Developmental and Stem Cell Biology, principal faculty member at the Harvard Stem Cell Institute and Assistant Professor of Stem Cell and Regenerative Biology at Harvard University. “This study indicates the presence of renewing muscle stem cells in adult skeletal muscle and demonstrates the potential benefit of stem cell therapy for the treatment of muscle degenerative diseases such as muscular dystrophy. [lien] [EN]

Scientists clone mice from adult skin stem cells

For cells that hold so much promise, stem cells’ potential has so far gone largely untapped. But new research from Rockefeller University and Howard Hughes Medical Institute scientists now shows that adult stem cells taken from skin can be used to clone mice using a procedure called nuclear transfer. The findings are reported in the Feb. 12 online edition of the Proceedings of the National Academy of Sciences. Caption: Using a technique called nuclear transfer, mice were cloned using adult skin stem cells (right) and a more differentiated type of skin cell (left). The mouse on the right is almost two years old and the mouse on the right is one and a half. Credit: Jinsong Li, Postdoc in the Mombaerts Laboratory, Rockefeller University Embryonic stem cells have received the most press for their potential to generate healthy cells and tissues that could replace damaged or diseased organs. [lien] [EN]

Medium is the message for stem cells in search of identities

Embryonic stem cells, prized for their astonishing ability to apparently transform into any kind of cell in the body, acquire their identities in part by interacting with their surroundings - even when they are outside of the body in a laboratory dish, University of Florida scientists report. Using an animal model of embryonic stem cell development, researchers with UF’s McKnight Brain Institute have begun to answer one of the most fundamental questions in science - how does a batch of immature cells give rise to an organ as extraordinarily complex as the human brain? The findings, to be published this week in the Proceedings of the National Academy of Sciences, may one day help scientists create laboratory environments to grow specialized cells that can be transplanted into patients to treat epilepsy. [lien] [EN]