ALL STEM CELLS

Hematopoietic stem cells (HSCs) undergo dramatic expansion in the fetal liver before migrating to their definitive site in the bone marrow. Khan et al. identify portal vessel–associated Nestin+NG2+pericytes as critical HSC niche components (see the Perspective by Cabezas- Wallscheid and Trumpp). The portal vessel niche and HSCs expand according to fractal geometries, suggesting that niche cells—rather than factors expressed by the niche—drive HSC proliferation.
After birth, arterial portal vessels transform into portal veins, and lose Nestin+NG2+ pericytes. When this happens, the niche is lost and HSCs migrate away from the neonatal liver. — BAP
8 January 2016
Source : sciencemag.org