Dimitroff et al. (page 1277) appear to have uncovered the major “homing receptor” that allows hematopoietic progenitor cells (HPCs) to enter bone marrow. The discovery of the receptor, a novel glycoform of CD44, could form the basis for improvements in HPC selection for hematopoietic stem cell transplants.
The endothelial proteins that are believed to mediate homing include E-selectin. This membrane protein functions in the “rolling” phase of leukocyte–endothelial adhesive interactions, and its expression on vascular endothelium is typically induced by inflammatory stimuli. But its expression on bone marrow sinusoidal endothelium, where it is believed to mediate HPC homing to marrow, is constitutive. Until now, the corresponding ligands on HPCs have remained poorly characterized.
In the new work, the authors used a novel blot rolling adherence assay to survey all possible E-selectin ligands expressed on human HPCs. In addition to...
