The findings, reported in the advance, on-line issue of Nature on Oct. 12, contrast with previous studies that have suggested adult stem cells derived from the bone marrow -- a spongy tissue inside bones that makes blood cells -- were capable of specializing not just into blood cells, but into cells of the brain, heart and other tissues. These studies have raised hopes that cells that are progenitors of blood could be used to replace damaged tissue in critical organs.
The new findings provide the first indication that cell fusion, rather than differentiation, occurs when bone marrow-derived cells migrate to the heart and the brain of mice. They also support previous studies showing fusion of blood cells in liver, and in cell-culture.
Given this evidence, the researchers say, clinical trials to study whether implanted bone marrow-derived cells could be used to replenish damaged cells in patients with diseases of the heart, brain and liver should be postponed until more research has been conducted.
"Our study raises serious questions about whether bone marrow-derived cells are capable of trans-differentiation," says the senior author of the study, Arturo Alvarez-Buylla, PhD, professor of neurosurgery at University of California, San Francisco (UCSF).
"The finding raises major questions about the plasticity of adult blood stem cells," says co-author Sean J. Morrison, PhD, a Howard Hughes Medical Institute assistant investigator and assistant professor of internal medicine and of cell and development biology at
Contact: Jennifer O'Brien
University of California - San Francisco