Scientists find previously unknown receptors on adult stem cells

Sur le même thème que "Scientists find previously unknown receptors on adult stem cells"

Researchers map gene that regulates adult stem cell growth

The researchers genetically mapped a stem cell gene and its protein product, Laxetin, and building on that effort, carried the investigation all the way through to the identification of the gene itself. This is the first time such a complete study on a stem cell gene has been carried out. This particular gene is important because it helps regulate the number of adult stem cells in the body, particularly in bone marrow. Now that it has been identified, researchers hope the gene, along with its protein product Latexin, can be used clinically, such as for ramping up the stem cell count in cancer patients undergoing chemotherapy and bone marrow transplantation. The researchers agreed that this very process is not only interesting, but important because of its usefulness in a wide variety of future genetics studies. [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]

Scientists Discover Key to Growing New Stem Cells

Scientists at Duke University Medical Center have demonstrated they can grow human stem cells in the laboratory by blocking an enzyme that naturally triggers stem cells to mature and differentiate into specialized cells. The discovery may enable scientists to rapidly grow stem cells and transplant them into patients with blood disorders, immune defects and select genetic diseases, said the Duke researchers. Stem cells are the most flexible cells in the body, continually dividing into new stem cells or into specialized cells that carry out specific roles in the body. But little is known about how stem cells choose their fate. The Duke team focused on “hematopoietic” or blood stem cells. [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. [lien] [EN]

Scientists discover new, readily available source of stem cells

Scientists have discovered a new source of stems cells and have used them to create muscle, bone, fat, blood vessel, nerve and liver cells in the laboratory. The first report showing the isolation of broad potential stem cells from the amniotic fluid that surrounds developing embryos was published in Nature Biotechnology. “Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well,” said Anthony Atala, M.D., senior researcher and director of the Institute for Regenerative Medicine at Wake Forest University School of Medicine. Atala announced the breakthrough with colleagues from Wake Forest University School of Medicine and Harvard Medical School. “It has been known for decades that both the placenta and amniotic fluid contain multiple progenitor cell types from the developing embryo. [lien] [EN]

Scientists eliminate viral vector in stem cell reprogramming

Previously, Dr. Shinya Yamanaka of Kyoto University and the Gladstone Institute of Cardiovascular Disease, had shown that adult cells can be reprogrammed to become embryonic stem cell–like using a cancer-causing oncogene as one of the four genes required to reprogram the cells, and a virus to transfer the genes into the cells. In the last year, Dr. Yamanaka and other labs showed that the oncogene, c-Myc, is not needed. However the use of viruses that integrate into the genome prohibit use of iPS cells for regenerative medicine because of safety concerns: its integration into the cell’s genome might activate or inactivate critical host genes. Now Dr. Yamanaka’s laboratory in Kyoto has eliminated the need for the virus. In a report published this week in Science. [lien] [EN]

UC Irvine scientists find new way to sort stem cells

UC Irvine scientists have found a new way to sort stem cells that should be quicker, easier and more cost-effective than current methods. The technique could in the future expedite therapies for people with conditions ranging from brain and spinal cord damage to Alzheimer's and Parkinson's diseases. The method uses electrodes on a tiny, inch-long glass slide to sort cells by their electric charges and has been used in cancer research. The stem cell field suffers from a lack of tools for identifying and sorting cells. This important discovery could add a new tool to current sorting methods, which generally require expensive, bulky equipment. “For therapeutic purposes, we want stem cells to turn into specific cell types once they have been transplanted. [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]

Human embryonic stem cells display a unique pattern of chemical modification to DNA

Scientists have found that the DNA of human embryonic stem cells is chemically modified in a characteristic, predictable pattern. This pattern distinguishes human embryonic stem cells from normal adult cells and cell lines, including cancer cells. The study, which appears online today in Genome Research, should help researchers understand how epigenetic factors contribute to self-renewal and developmental pluripotence, unique characteristics of human embryonic stem cells that may one day allow them to be used to replace diseased or damaged cells with healthy ones in a process called therapeutic cloning. Embryonic stem cells are derived from embryos that are undergoing a period of intense cellular activity. [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]

Progress being made in exploring potential use of stem cells to treat heart disease

Scientists are making headway in exploring the potential future use of stem cells to treat heart disease, according to a review article in the current issue of Nature (June 29, 2006). Authored by Gladstone Institute of Cardiovascular Disease Director Deepak Srivastava, MD, and Gladstone Institutes postdoctoral scholar Kathryn Ivey, PhD, the paper cites a better understanding of the following areas of research: > the developmental processes within the heart that can be reproduced using pluripotent embryonic stem cells (these are early stem cells that can grow into almost any cell type) > the cues that control multipotent cardiac stem cells (these stem cells, which have less developmental potential than embryonic stem cells. [lien] [EN]

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. Hockemeyer and Frank Soldner are first authors on the article and postdoctoral researchers in Whitehead Member Rudolf Jaensich’s lab. [lien] [EN]

Stretching bone marrow stem cells pushes them towards becoming blood vessel

When stretched, a type of adult stem cell taken from bone marrow can be nudged towards becoming the type of tissue found in blood vessels, according to a new study by bioengineers at the University of California, Berkeley. Researchers placed mesenchymal stem cells onto a silicone membrane that was stretched longitudinally once every second. It was a cellular workout routine that helped point the bone marrow stem cell in the direction of becoming the smooth muscle tissue of vascular walls. The findings, published today (Monday, Oct. 23) in the online early edition of the Proceedings of the National Academy of Sciences, highlight the importance of mechanical forces in stem cell differentiation. Mesenchymal stem cells have the ability to turn into different types of connective tissue including bone. [lien] [EN]