Signaling Molecule May Help Stem Cells Make Bone Despite Age, Disease

A signaling molecule that helps stem cells survive in the naturally low-oxygen environment inside the bone marrow may hold clues to helping the cells survive when the going gets tougher with age and disease, researchers report. They hope their findings, reported online on March 5, 2013 in the open-access journal PLOS ONE, will result in better therapies to prevent bone loss in aging and enhance success of stem cell transplants for a wide variety of conditions from heart disease to cerebral palsy and cancer. The scientists found that inside the usual, oxygen-poor niche of mesenchymal stem cells, stromal cell-derived factor-1, or SDF-1, turns on a survival pathway called autophagy that helps the cells stay in place and focused on making bone, said Dr. William D. Hill, stem cell researcher at the Medical College of Georgia (MCG) at Georgia Regents University (GRU) and the study's corresponding author. Unfortunately, with age or disease, SDF-1 appears to change its tune, instead reducing stem cells' ability to survive and stay in the bone marrow, said Samuel Herberg, GRU graduate student and the study's first author. Additionally, cells that do stay put may be less likely to make bone and more likely to turn into fat cells in the marrow. The researchers believe it's the changes in the normal environment that come with age or illness, including diminished nutrition, that prompt SDF-1's shifting role. "You put new cells in there and, all of the sudden, you put them in a neighborhood where they are being attacked," Dr. Hill said.
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