Stem cells hold their breath.

摘要

In this issue of Blood, Winkler and colleagues use blood perfusion to define and characterize 2 distinct HSC populations in the BM, demonstrating that the most primitive HSCs reside in a BM niche with negligible perfusion. Over the past decade there has been great interest in in vivo regulatory mechanisms of hematopoietic stem cells (HSCs). While much has been learned regarding both the intrinsic and extrinsic determinants of stem cell function, pinpointing the location of the cells in the adult bone marrow (BM) has been elusive. Studies by different groups have shown that cells of the osteoblast lineage are key components of the HSC niche, correlating with previous studies demonstrating that HSCs are preferentially located at the en-dosteal surface of bone.