Submitted April 6, 2007
Accepted September 8, 2007
Wnt signaling promotes hemato-endothelial cell development from human embryonic stem cells
Petter S. Woll, Julie K. Morris, Matt S. Painschab, Rebecca K. Marcus, Aimee D. Kohn, Travis L. Biechele, Randall T. Moon, and Dan S. Kaufman*
Stem Cell Institute and Department of Medicine, University of Minnesota, Minneapolis, MN, United States
Howard Hughes Medical Institute, Department of Pharmacology, and Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, WA, United States
* Corresponding author; email: kaufm020{at}umn.edu.
Human embryonic stem cells (hESCs) provide an important means to effectively study soluble and cell-bound mediators that regulate development of early blood and endothelial cells in a human model system. Here, several complementary methods are utilized to demonstrate canonical Wnt signaling is important for development of hESC-derived cells with both hematopoietic and endothelial potential. Analyses using both standard flow cytometry, as well the more detailed high-throughput image scanning flow cytometry, characterizes sequential development of distinct early developing CD34brightCD31+Flk1+ cells and a later population of CD34dimCD45+ cells. While the CD34brightCD31+Flk1+ have a more complex morphology and can develop into both endothelial cells and hematopoietic cells, the CD34dimCD45+ cells have a simpler morphology and give rise to only hematopoietic cells. Treatment with dickkopf1 to inhibit Wnt signaling results in a dramatic decrease in development of cells with hemato-endothelial potential. Additionally, activation of the canonical Wnt signaling pathway in hESCs by co-culture with stromal cells that express Wnt1, but not use of noncanonical Wnt5 expressing stromal cells, results in an accelerated differentiation and higher percentage of CD34brightCD31+Flk1+ cells at earlier stages of differentiation. These studies effectively demonstrate the importance of canonical Wnt signaling to mediate development of early hemato-endothelial progenitors during human development.
