Pluripotent stem cells (PSCs) represent an alternative hematopoietic stem cell (HSC) source for treating hematopoietic disease. The limited engraftment of human PSC–derived (hPSC-derived) multipotent progenitor cells (MPP) has hampered the clinical application of these cells and suggests that MPP require additional cues for definitive hematopoiesis. We hypothesized that the presence of a vascular niche that produces Notch ligands jagged-1 (JAG1) and delta-like ligand-4 (DLL4) drives definitive hematopoiesis. We differentiated hes2 human embryonic stem cells (hESC) and Macaca nemestrina–induced PSC (iPSC) line-7 with cytokines in the presence or absence of endothelial cells (ECs) that express JAG1 and DLL4. Cells cocultured with ECs generated substantially more CD34+CD45+ hematopoietic progenitors compared with cells cocultured without ECs or with ECs lacking JAG1 or DLL4. EC-induced cells exhibited Notch activation and expressed HSC-specific Notch targets RUNX1 and GATA2. EC-induced PSC-MPP engrafted at a markedly higher level in NOD/SCID/IL-2 receptor γ chain–null (NSG) mice compared with cytokine-induced cells, and low-dose chemotherapy-based selection further increased engraftment. Long-term engraftment and the myeloid-to-lymphoid ratio achieved with vascular niche induction were similar to levels achieved for cord blood–derived MPP and up to 20-fold higher than those achieved with hPSC-derived MPP engraftment. Our findings indicate that endothelial Notch ligands promote PSC-definitive hematopoiesis and production of long-term engrafting CD34+ cells, suggesting these ligands are critical for HSC emergence.

J Clin Invest. February 9, 2015; doi:10.1172/JCI79328

Jennifer L. Gori,1  Jason M. Butler,2,3  Yan-Yi Chan,1  Devikha Chandrasekaran,1  Michael G. Poulos,2,3  Michael Ginsberg,4  Daniel J. Nolan,4  Olivier Elemento,5  Brent L. Wood,6,7  Jennifer E. Adair,1,8  Shahin Rafii,9 and Hans-Peter Kiem,1,6,8

1Clinical Research Division, Fred Hutchinson Cancer Research Center (FHCRC), Seattle, Washington, USA. 2Department of Genetic Medicine, Ansary Stem Cell Institute, and 3Department of Surgery, Weill Cornell Medical College, New York, New York, USA. 4Angiocrine Bioscience, New York, New York, USA. 5HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York, USA. 6Department of Pathology, 7Department of Laboratory Medicine, and 8Department of Medicine, University of Washington, Seattle, Washington, USA. 9Howard Hughes Medical Institute, Ansary Stem Cell Institute, Department of Genetic Medicine, Weill Cornell Medical College, New York, New York, USA.