When is a stem cell not really a stem cell?August 27, 2007Working with embryonic mouse brains, a team of Johns Hopkins scientists seems to have discovered an almost-too-easy way to distinguish between "true" neural stem cells and similar, but less potent versions. Their finding, reported this week in Nature, could simplify the isolation of stem cells not only from brain but also other body tissues. What the researchers identified is a specific protein "signal" that appears to prevent neural stem cells - the sort that might be used to rebuild a damaged nervous system - from taking their first step toward becoming neurons. "Stem cells don't instantly convert into functional adult tissue," says author Nicholas Gaiano, Ph.D., assistant professor at the Institute for Cell Engineering. "They undergo a stepwise maturation where they gradually shed their stem cell properties." The first step turns stem cells into "progenitor" cells by dictating how signals downstream of a protein called Notch, which regulates stem cells in many different tissues, are transmitted. One well known target of Notch is a protein called CBF1. To help study Notch signaling further, Gaiano and his team created genetically engineered mouse embryos that glow green when CBF1 is turned on.
To their surprise, they noticed that during brain development some of the brain cells generally thought to be neural stem cells stopped glowing, indicating that the CBF1 protein was no longer active in them. A closer look revealed that those cells that went dark were in fact no longer true neural stem cells, which can form all major brain cell types, but instead had aged into progenitor cells, which form mostly neurons. They tested whether CBF1 was the critical switch by chemically knocking out the protein in neural stem cells. The knockout got the stem cells to rapidly convert to progenitor cells. "However, if we activated the CBF1 protein in progenitor cells we couldn't get them to shift back into stem cells," says Gaiano. "So whatever happens biochemically once CBF1 is turned off seems to create a one-way street." Another recent study, using the mouse line generated by the Gaiano group, found that CBF1 signaling may play the same role in blood stem cells, leading Gaiano to suspect that his team's discovery might be a general "switch" distinguishing stem cells from progenitors in many different tissues. Johns Hopkins Medical Institutions | |||||||||||||||||||||
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Related Stem Cells News Articles Sugar study is sweetener for stem cell science Scientists at The University of Manchester are striving to discover how the body's natural sugars can be used to create stem cell treatments for heart disease and nerve damage - thanks to a £370,000 funding boost. MIT identifies cells for spinal-cord repair A researcher at MIT's Picower Institute for Learning and Memory has pinpointed stem cells within the spinal cord that, if persuaded to differentiate into more healing cells and fewer scarring cells following an injury, may lead to a new, non-surgical treatment for debilitating spinal-cord injuries. Standards in stem cell research Standards in stem cell research help both scientists and regulators to manage uncertainty and the unknown, according to new research funded by the Economic and Social Research Council. Researchers grow human blood vessels in mice from adult progenitor cells For the first time, researchers have successfully grown functional human blood vessels in mice using cells from adult human donors - an important step in developing clinical strategies to grow tissue, researchers report in Circulation Research: Journal of the American Heart Association. Predicting acute GVHD by gene expression could improve liver stem cell transplant outcomes Many cell transplants involve the use of stem cells from another human being (known as an allograft), which raises the major concern of the potential for acute graft-versus-host disease (GVHD). Stem cell chicken and egg debate moves to unlikely arena: the testes Logic says it has to be the niche. As air and water preceded life, so the niche, that hospitable environment that shelters adult stem cells in many tissues and provides factors necessary to keep them young and vital, must have emerged before its stem cell dependents. Vitamin A pushes breast cancer to form blood vessel cells Researchers at Georgetown University Medical Center have discovered that vitamin A, when applied to breast cancer cells, turns on genes that can push stem cells embedded in a tumor to morph into endothelial cells. These cells can then build blood vessels to link up to the body's blood supply, promoting further tumor growth. UNC study ties ending moderate drinking to depression Scientific evidence has long suggested that moderate drinking offers some protection against heart disease, certain types of stroke and some forms of cancer. Myostatin inhibitors may improve recovery of wartime limb injuries Inhibiting a growth factor that keeps muscles from getting too big may optimize recovery of injured soldiers, researchers say. Human embryonic stem cells developed from 4-cell embryo; world first may lessen ethical concerns For the first time in the world scientists have succeeded in developing human embryonic stem cells (hESCs) from a single cell, or blastomere, of a 4-cell stage embryo. More Stem Cells News Articles |
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