Fig. 5
From: Molecular and cellular mechanisms of aging in hematopoietic stem cells and their niches
BM HSC niches. Endosteal/arteriolar niches are localized close to the endosteal region of BM, which are populated by CD31hiEmcnhi type-H ECs and osteogenic-biased MSC-SCs in the arteriolar capillaries at the distal end of the arterial network (transition zone vessels have substantial branching). Sinusoid niches are localized to the central region of BM and are composed of type-L ECs and adipogenic-biased MSC-SCs. In addition, MKs, Mφ and Treg cells also function as niche cells to maintain HSC quiescence, retain HSCs within their BM niche, and to protect HSCs from immune attack. In addition, the adrenergic sympathetic nerve also functions as niche component for HSCs by regulating HSC relocation between niches