Stem Cell Modeling of Core Binding Factor Acute Myeloid Leukemia

Figure 3

Simplified schematics of the endosteal and vascular hematopoietic niches. Two hematopoietic niches have been identified in the bone marrow, even though their nature as anatomical rather than functional entities is still a matter of debate. The first one, called the “endosteal niche” (A), is located near the endosteum and thought to harbour mainly quiescent HSC capable of extensive self-renewal. It is thought to be composed of osteoblasts (represented as a layer of “grey triangles” in the figure), mesenchymal stromal cells (“grey octagons”), megakaryocytes (“black decagons”), HSC (“white circles”), early committed HPP (“light grey circles”), and hematopoietic precursors at various degrees of commitment (“dark grey circles”). The second one, called the “vascular niche” (B), is located around the central vessel in the bone marrow and seems to harbour mainly rapidly proliferating HSC and HPP. It is composed by endothelial cells (boarding the central vessel), mesenchymal stromal cells (“grey octagons”), HSC (“white circles”), HPP (“light grey circles”), hematopoietic precursors at various degrees of commitment (“dark grey circles”), macrophages (“black triangles”), and megakaryocytes (“black decagons”). According to a theory, HSC would move from the endosteal to the vascular niche as they switch from a “resting” to a “proliferating” mode.