| [ Summary ] |
Recent studies concerning hematopoietic stem cell (HSC) niches suggest that HSCs are associated with osteoblasts. However, the localization of HSCs within bone marrow and the nature of HSC niches remain unclear. It has been shown recently that CXCL12-CXCR4 chemokine signaling plays an essential role in maintaining a quiescent HSC pool, and that cells expressing high levels of CXCL12, called CXCL12-abundant reticular (CAR) cells are scattered throughout bone marrow and appear to be a key component of HSC niches, including both vascular and endosteal niches in adult bone marrow. It will be interesting to know if CAR cells are involved in bone remodeling. |