Using a sophisticated way of examining the "humanness" of mouse heart cells, researchers report in the December 21 issue of the journal Circulation (which was published online December 13) that two months after mice with ailing hearts were treated with human stem cells, about two percent of cells in their heart showed evidence of a human genetic marker.
Furthermore, researchers described, for the first time, how these human master cells use different ways to become two distinct kinds of cells needed in the heart. Human stem cells primarily "fuse" onto mouse cardiac cells to produce new muscle (myocyte) cells that have both human and mouse DNA. But to form new blood vessel cells, they "differentiate" or mature by themselves, presumably to patch damaged mouse blood vessels with human cells.
These findings should help resolve debate within the field as to whether stem cell transfer actually creates new types of cells that last within a heart, says the study's lead author Edward T. H. Yeh, M.D., professor and chair of The University of Texas M. D. Anderson's Department of Cardiology.
"We have shown that these stem cells create both types of tissue needed to repair areas of damage, that they use two different ways to develop them, and that these cells can persist for up to a year, which is a long time in the life of a mouse," he says.
"Most of all, this study is important because it begins to explain why stem cells can help a heart heal," he adds. "Clinical trials that use bone marrow stem cells in people with heart damage have shown promise
Contact: Nancy Jensen
University of Texas M. D. Anderson Cancer Center