Endothelial Cells Are Essential for the Self-Renewal and Repopulation of Notch-Dependent Hematopoietic Stem Cells

• Published in: Cell stem cell 2010-03, Vol.6 (3), p.251-264
• Main Authors: Butler, Jason M., Nolan, Daniel J., Vertes, Eva L., Varnum-Finney, Barbara, Kobayashi, Hideki, Hooper, Andrea T., Seandel, Marco, Shido, Koji, White, Ian A., Kobayashi, Mariko, Witte, Larry, May, Chad, Shawber, Carrie, Kimura, Yuki, Kitajewski, Jan, Rosenwaks, Zev, Bernstein, Irwin D., Rafii, Shahin
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cell Communication; Cell differentiation, maturation, development, hematopoiesis; Cell Lineage; Cell physiology; Cell Proliferation; Cells, Cultured; Coculture Techniques; Culture Media, Conditioned; Endothelial Cells - cytology; Endothelial Cells - metabolism; Fundamental and applied biological sciences. Psychology; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - metabolism; Ligands; Mice; Mice, Knockout; Molecular and cellular biology; Receptor, Notch1 - deficiency; Receptor, Notch1 - metabolism; Receptor, Notch2 - deficiency; Receptor, Notch2 - metabolism; Signal Transduction; STEMCELL
• ISSN: 1934-5909; 1875-9777
• DOI: 10.1016/j.stem.2010.02.001

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. [Display omitted] ► Coculture with endothelial cells promotes HSC expansion and self-renewal ► Endothelial cell effect on HSCs mediated by Notch signaling ► In vivo, sinusoidal endothelial cells (SECs) express Notch ligands ► Blocking vessel remodeling impairs hematopoietic recovery after irradiation