Scientists Discover Key to Growing New Stem Cells

Sur le même thème que "Scientists Discover Key to Growing New Stem Cells"

Scientists unlock mystery of embryonic stem cell signaling pathway

A newly discovered small molecule called IQ-1 plays a key role in preventing embryonic stem cells from differentiating into one or more specific cell types, allowing them to instead continue growing and dividing indefinitely, according to research performed by a team of scientists who have recently joined the stem-cell research efforts at the Keck School of Medicine of the University of Southern California. Their findings are being published in the Proceedings of the National Academy of Sciences. This discovery takes scientists another step closer to being able to grow embryonic stem cells without the “feeder layer” of mouse fibroblast cells that is essential for maintaining the pluripotency of embryonic stem cells. [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]

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 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]

Neural stem cell differentiation factor discovered

Neural stem cells represent the cellular backup of our brain. These cells are capable of self-renewal to form new stem cells or differentiate into neurons, astrocytes or oligodendrocytes. Astrocytes have supportive functions in the environment of neurons, while oligodendrocytes form the myelin layer around axons in order to accelerate neuronal signal transmission. But how does a neural stem cell „know” which way it is supposed to develop? On the molecular level receptors of the Notch family play a significant role in this process. So far, only stimulating extracellular ligands of Notch receptors had been described. Biochemists of Goethe University Medical School now describe a long time assumed but not yet identified soluble Notch inhibitor. [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]

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]

Stem cell breakthrough gives new hope to sufferers of muscle-wasting diseases

An experimental procedure that dramatically strengthens stem cells’ ability to regenerate damaged tissue could offer new hope to sufferers of muscle-wasting diseases such as myopathy and muscular dystrophy, according to researchers from the University of New South Wales (UNSW). The world-first procedure has been successfully used to regrow muscles in a mouse model, but it could be applied to all tissue-based illnesses in humans such as in the liver, pancreas or brain, the researchers say. The research team, which is based at UNSW and formerly from Sydney’s Westmead Children’s Hospital, adapted a technique currently being trialled in bone marrow transplantation. Adult stem cells are given a gene that makes them resistant to chemotherapy, which is used to clean out damaged cells and allow the new stem cells to take hold. [lien] [EN]

Scientists discover key to manipulating fat

In what they call a “stunning research advance,” investigators at Georgetown University Medical Center have been able to use simple, non-toxic chemical injections to add and remove fat in targeted areas on the bodies of laboratory animals. They say the discovery, published online in Nature Medicine on July 1, could revolutionize human cosmetic and reconstructive plastic surgery and treatment of diseases associated with human obesity. Investigators say these findings may also, over the long-term, lead to better control of metabolic syndrome, which is a collection of risk factors that increase a patient's chances of developing heart disease, stroke, and diabetes. Sixty million Americans were estimated to be affected by metabolic syndrome in 2000, according to a study funded by the Centers for Disease Control in 2004. [lien] [EN]

Study unlocks stem cell DNA secrets

In a groundbreaking study led by an eminent molecular biologist at Florida State University, researchers have discovered that as embryonic stem cells turn into different cell types, there are dramatic corresponding changes to the order in which DNA is replicated and reorganized. The findings bridge a critical knowledge gap for stem cell biologists, enabling them to better understand the enormously complex process by which DNA is repackaged during differentiation — when embryonic stem cells, jacks of all cellular trades, lose their anything-goes attitude and become masters of specialized functions. Caption: In mammalian nuclei, replication takes place at punctate sites or foci. Early-replicating foci localize to the interior of the nucleus (green). [lien] [EN]

The making of an intestinal stem cell

Researchers have found the factor that makes the difference between a stem cell in the intestine and any other cell. The discovery reported in the March 6th issue of the journal Cell, a Cell Press publication, is an essential step toward understanding the biology of the stem cells, which are responsible for replenishing all other cells in the most rapidly self-renewing tissue in mammals. It may also have implications for colon cancer, according to the researchers. The report finds evidence that a transcription factor called Achaete scute-like 2 (Ascl2) switches on the stem cell program in intestinal cells. Transcription factors are genes that control other genes. “This transcription factor makes these stem cells tick. [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 discover new way to enhance stem cells to stimulate muscle regeneration

Scientists at the Ottawa Hospital Research Institute (OHRI) and the University of Ottawa have discovered a powerful new way to stimulate muscle regeneration, paving the way for new treatments for debilitating conditions such as muscular dystrophy. The research, to be published in the June 5 issue of Cell Stem Cell, shows for the first time that a protein called Wnt7a increases the number of stem cells in muscle tissue, leading to accelerated growth and repair of skeletal muscle. “This discovery shows us that by targeting stem cells to boost their numbers, we can improve the body’s ability to repair muscle tissue,” said senior author Dr. Michael Rudnicki. Dr. Rudnicki is the Scientific Director of Canada’s Stem Cell Network and a Senior Scientist at OHRI and Director of OHRI’s Sprott Centre for Stem Cell Research. [lien] [EN]