Nearly three decades after the discovery of the hematopoietic stem cell, a team led by Ludwig Cancer Research scientist Irv Weissman has identified a unique molecular marker that allows them to isolate the longest-living version of such cells, the one that gives rise to all cellular components of the blood and immune system. If confirmed, the finding—published in the February 11 issue of the journal Nature—will help settle long-standing controversies about the identity of these stem cells and their cellular supporters, permitting their detailed examination and opening the door to their cultivation in the laboratory and clinic.
In 1988, Weissman and his colleagues isolated the hematopoietic stem cell, which generates the body’s blood and immune cells. Over the years it has, however, become clear that hematopoietic stem cells actually come in two flavors. Most are short-term HSCs that lose their powers of replication over time; only a small fraction are the ones everybody is looking for—long-term HSCs that can replicate indefinitely and are critical to lifelong blood production.
To understand how other cells nurture the HSC, researchers need to isolate and study only the long-term HSC. Weissman and his colleagues seem to have finally found how to do that. “In this paper we have found a single marker that, in the entire bone marrow, is only found in these long-term stem cells,” said Weissman, who is the director of the Ludwig Center at Stanford, as well as the Stanford Institute for Stem Cell Biology and Regenerative Medicine.
A more detailed news release about this study can be found here.