Endothelial cells are essential for the self-renewal and repopulation of Notch-dependent hematopoietic stem cells.

Publication Type:

Journal Article

Source:

Cell stem cell, Volume 6, Issue 3, p.251-64 (2010)

Keywords:

2010, Animals, Cell Communication, Cell Lineage, Cell Proliferation, Cells, Cultured, Clinical Research Division, Coculture Techniques, Culture Media, Conditioned, Endothelial Cells, Flow Cytometry Core Facility, Genomics Core Facility, Hematopoietic Stem Cells, Ligands, MICE, Mice, Knockout, Receptor, Notch1, Receptor, Notch2, Shared Resources, Signal Transduction

Abstract:

Bone marrow endothelial cells (ECs) are essential for reconstitution of hematopoiesis, but their role in self-renewal of long-term hematopoietic stem cells (LT-HSCs) is unknown. We have developed angiogenic models to demonstrate that EC-derived angiocrine growth factors support in vitro self-renewal and in vivo repopulation of authentic LT-HSCs. In serum/cytokine-free cocultures, ECs, through direct cellular contact, stimulated incremental expansion of repopulating CD34(-)Flt3(-)cKit(+)Lineage(-)Sca1(+) LT-HSCs, which retained their self-renewal ability, as determined by single-cell and serial transplantation assays. Angiocrine expression of Notch ligands by ECs promoted proliferation and prevented exhaustion of LT-HSCs derived from wild-type, but not Notch1/Notch2-deficient, mice. In transgenic notch-reporter (TNR.Gfp) mice, regenerating TNR.Gfp(+) LT-HSCs were detected in cellular contact with sinusoidal ECs. Interference with angiocrine, but not perfusion, function of SECs impaired repopulation of TNR.Gfp(+) LT-HSCs. ECs establish an instructive vascular niche for clinical-scale expansion of LT-HSCs and a cellular platform to identify stem cell-active trophogens.