1. Getting blood from bone: An emerging understanding of the role that osteoblasts play in regulating hematopoietic stem cells within their niche 
Yusuke Shiozawa, Russell S. Taichman 
Experimental Hematology 
Volume 40, Issue 9, Pages (September 2012)
DOI: /j.exphem
Copyright © 2012 ISEH - Society for Hematology and Stem Cells Terms and Conditions

2. Figure 1
The model of ecological hematopoietic stem cell niche. HSC homing, maintenance, and differentiation depend on their specific microenvironment (or niche). In the bone marrow there are at least two major HSC niches. The vascular niche, which is a gateway for HSCs between the periphery and marrow that likely facilitates the proliferation and differentiation of HSCs, while the osteoblastic niche likely maintains self-renewal and quiescence of HSCs. Osteoclasts are also known to participate in niche function, partially by regulating HSC mobilization. In addition, there are growing indications that other types of cells, including fibroblasts, CXCL12-expressing reticular cells, nestin-expressing MSCs, and adipocytes, also serve as the HSC niche in the marrow. Homing of stem cells is mainly regulated thorough CXCL12 expressed by the HSC niche. Interestingly, circadian rhythm is involved in these relationships by regulating CXCL12 expression in the marrow. As such, a variety of the marrow cells can dynamically affect each other and participate in hematopoiesis.
Experimental Hematology  , DOI: ( /j.exphem )
Copyright © 2012 ISEH - Society for Hematology and Stem Cells Terms and Conditions