The Haematopoietic Stem Cell Niche: New Insights into the Mechanisms Regulating Haematopoietic Stem Cell Behaviour

Figure 1

Endosteal and vascular niches are subcompartments of a single niche. HSCs located at the endosteum are more quiescent and have a greater self-renewal capacity due to a variety of cytokines, adhesion molecules, and hypoxia. HSCs located close to the sinusoid endothelium have reduced self-renewal capacity and are cycling more rapidly, due to higher oxygen levels and SCF. However, nearly all HSCs reside adjacent to CAR cells and in close proximity to the sinusoid endothelium. The cells of the vascular niche communicate with cells of the endosteal niche, and the subtle balance of factors from these subcompartments governs the behaviour of the HSCs.