Genes & Cells

Rejection denied
A life-threatening complication of bone marrow transplants may be stopped by reducing damage to stem cells that regenerate the lining of the intestines. Graft-versus-host disease results when immune cells from transplanted bone marrow begin attacking the recipient’s body. The disease stems partly from pretransplant radiation damage to intestinal stem cells, researchers from Kyushu University in Japan report January 31 in the Journal of Experimental Medicine. Giving mice a protein called R-spondin1 triggers cellular processes that protect the stem cells and head off graft-versus-host disease, the team found. —Tina Hesman Saey

Blood stem cell flexibility
There are two types of blood-forming stem cells in this world, scientists thought — one that churns out trillions of blood cells every day, and a reserve that only kicks in to regenerate the blood system when under attack. Now researchers in Switzerland report online February 7 in the Journal of Experimental Medicine that blood-forming stem cells in mice take on both identities throughout their lifetimes. Sometimes the cells divide rapidly and make blood. Other times the cells rest. The finding could help explain why stem cells seem to age at similar rates despite some seeming to work harder than others. —Tina Hesman Saey

Smell cell’s age matters
Young and old cells help mice smell in different ways, a study published online February 6 in Nature Neuroscience suggests. Researchers led by Fumiaki Imamura of Yale University School of Medicine labeled baby brain cells that transmit odor information and watched as the cells traveled to their final destinations. Cells with early birthdates preferentially settled in one part of the brain, while cells born later settled elsewhere, the team found. Thin projections from the older cells guided younger cells. Understanding how these cells organize by age may help researchers uncover how the brain senses and responds to distinct odors. —Laura Sanders