Hematopoietic stem cells (HSCs) differentiate into all cell types of the blood and can be used therapeutically to treat hematopoietic cancers and disorders. Despite decades of research, it is not yet possible to derive therapy-grade HSCs from pluripotent precursors. Analysis of HSC development in model organisms has identified some of the molecular cues that are necessary to instruct hematopoiesis in vivo, including Wnt9A, which is required during an early time window in zebrafish development. Although bona fide HSCs cannot be derived in vitro, it is possible to model human hematopoietic progenitor development by differentiating human pluripotent stem cells to hematopoietic cells. Herein, we modulate WNT9A expression during the in vitro differentiation of human embryonic stem cells to hematopoietic progenitor cells and demonstrate that WNT9A also regulates human hematopoietic progenitor cell development in vitro. Overexpression of WNT9A only impacts differentiation to CD34+/CD45+ cells during early time windows and does so in a dose-dependent manner. The cells that receive the Wnt signal—not the cells that secrete WNT9A—differentiate most efficiently to hematopoietic progenitors; this mimics the paracrine action of Wnt9a during in vivo hematopoiesis. Taken together, these data indicate that WNT9A is a conserved regulator of zebrafish and human hematopoietic development.
Bibliographical noteFunding Information:
Acknowledgments: This work was supported in part by the NIH/NHLBI under the Grant R01HL135205 and was made possible in part by the CIRM Major Facilities grant (FA1-00607) to the Sanford Consortium for Regenerative Medicine. JR was supported in part by the UCSD Interdisciplinary Stem Cell Training Program (CIRM TG2-01154) and by the American Heart Association Predoctoral Fellowship 16PRE27340012. E.G.S. and A.G.E. are Research Fellows of the NHMRC of Australia.
© 2018 by the authors. Licensee MDPI, Basel, Switzerland.
- Hematopoietic stem cells
- Human embryonic stem cells
- Induced pluripotent stem cells
- Wnt signaling