ANN ARBOR, Mich. -- In the rancorous public debate over federal research funding, stem cells are generally assigned to one of two categories: embryonic or adult. But that's a false dichotomy and an oversimplification. A new University of Michigan study adds to mounting evidence that stem cells in the developing fetus are distinct from both embryonic and adult stem cells.
In the last several years, stem cell researchers have realized that fetal stem cells comprise a separate class. They recognized, for example, that fetal blood-forming stem cells in umbilical cord blood behave differently than adult blood-forming stem cells after transplantation into patients.
Now a U-M team led by Sean Morrison has identified the first known gene, Sox17, required for the maintenance of blood-forming stem cells in fetal mice, but not in adult mice. The discovery provides a critical insight into the mechanisms that distinguish fetal blood-forming stem cells from their adult counterparts.
The findings could also lead to a deeper understanding of diseases such as childhood leukemias, said Morrison, director of the U-M Center for Stem Cell Biology and a Howard Hughes Medical Institute investigator. Childhood leukemias are cancers that afflict blood-forming cells and hijack normal stem cell self-renewal mechanisms.
"One of the next questions in our cross hairs is whether Sox17 gets inappropriately activated in certain childhood leukemias---and that's an idea that nobody had in their mind before this work," Morrison said. "If it's true, it'll give us a new target for cancer."
The Sox17 results will be published online July 26 in the journal Cell. U-M's Injune Kim is lead author of the paper; Morrison and U-M's Thomas Saunders are co-authors.
"Identification of Sox17 could also facilitate efforts to form blood-forming stem cells from human embryonic stem cells, a goal that could enhance bone marrow transplantation," Kim said.'"/>