Aortic Tissue as a Niche for Hematopoiesis
The stem cell theory of hematopoiesis predicts that all mature blood cell lineages circulating in the bloodstream or resident in tissues, arise via a hierarchy of hematopoietic progenitor cell (HPC) intermediates that are ultimately derived from hematopoietic stem cells (HSC). In the adult human subject, bone marrow resident HSC and HPC generate billions of circulating blood cells daily, ranging from the short-lived neutrophils and platelets to long-lived B and T lymphocytes and monocyte-macrophages. Recent interest in the roles of macrophages as modulators of angiogenesis1 and as participants in atheroma formation2 highlight the need to better understand the mechanisms of recruitment and retention of macrophages and their progenitor precursors within tissues. In this issue of Circulation, Psaltis and co workers3 identify clonogenic HPC activity in aortic adventitia (that is enriched in HPC compared to peripheral blood or muscle tissue) which appears skewed toward colony forming unit-macrophage (CFU-M) differentiation. In addition, stem cell antigen-1 (Sca-1) expressing cells in the aortic adventitia co-expressed a variety of HSC antigens and adoptive transfer of these cells into irradiated recipient mice led to low but sustained multilineage reconstitution; a property of HSC.. (SELECT FULL TEXT TO CONTINUE)
- Received December 6, 2011.
- Accepted December 9, 2011.
- Copyright © 2011, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited