The RUNX1 +24 Enhancer and P1 Promoter Identify a Unique Subpopulation of Hematopoietic Progenitor Cells Derived from Human Pluripotent Stem Cells

• Published in: Stem cells (Dayton, Ohio) Vol. 33; no. 4; pp. 1130 - 1141
• Main Authors: Ferrell, Patrick I., Xi, Jiafei, Ma, Chao, Adlakha, Mitali, Kaufman, Dan S.
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01-04-2015
• Subjects: Bone marrow; Core Binding Factor Alpha 2 Subunit - biosynthesis; Core Binding Factor Alpha 2 Subunit - genetics; Embryonic stem cells; Embryonic Stem Cells - physiology; Hematopoiesis; Hematopoiesis - physiology; Hematopoietic progenitor cells; Hematopoietic Stem Cells - physiology; Humans; Induced pluripotent stem cells; Induced Pluripotent Stem Cells - physiology; Medical research; Promoter Regions, Genetic - physiology; Stem cells; Hematopoietic progenitor cells; Embryonic stem cells; Hematopoiesis; Induced pluripotent stem cells
• ISSN: 1066-5099; 1549-4918
• DOI: 10.1002/stem.1940

Derivation of hematopoietic stem cells (HSCs) from human pluripotent stem cells remains a key goal for the fields of developmental biology and regenerative medicine. Here, we use a novel genetic reporter system to prospectively identify and isolate early hematopoietic cells derived from human embryonic stem cells (hESCs) and human induced pluripotent cells (iPSCs). Cloning the human RUNX1c P1 promoter and +24 enhancer to drive expression of tdTomato (tdTom) in hESCs and iPSCs, we demonstrate that tdTom expression faithfully enriches for RUNX1c‐expressing hematopoietic progenitor cells. Time‐lapse microscopy demonstrated the tdTom+ hematopoietic cells to emerge from adherent cells. Furthermore, inhibition of primitive hematopoiesis by blocking Activin/Nodal signaling promoted the expansion and/or survival of the tdTom+ population. Notably, RUNX1c/tdTom+ cells represent only a limited subpopulation of the CD34+CD45+ and CD34+CD43+ cells with a unique genetic signature. Using gene array analysis, we find significantly lower expression of Let‐7 and mir181a microRNAs in the RUNX1c/tdTom+ cell population. These phenotypic and genetic analyses comparing the RUNX1c/tdTom+ population to CD34+CD45+ umbilical cord blood and fetal liver demonstrate several key differences that likely impact the development of HSCs capable of long‐term multilineage engraftment from hESCs and iPSCs. Stem Cells 2015;33:1130–1141