The negative impact of Wnt signaling on megakaryocyte and primitive erythroid progenitors derived from human embryonic stem cells

Abstract

The Wnt gene family consists of structurally related genes encoding secreted signaling molecules that have been implicated in many developmental processes, including regulation of cell fate and patterning during embryogenesis. Previously, we found that Wnt signaling is required for primitive or yolk sac-derived-erythropoiesis using the murine embryonic stem cell (ESC) system. Here, we examine the effect of Wnt signaling on the formation of early hematopoietic progenitors derived from human ESCs. The first hematopoietic progenitor cells in the human ESC system express the pan-hematopoietic marker CD41 and the erythrocyte marker, glycophorin A or CD235. We have developed a novel serum-free, feeder-free, adherent differentiation system that can efficiently generate large numbers of CD41+CD235+ cells. We demonstrate that this cell population contains progenitors not just for primitive erythroid and megakaryocyte cells but for the myeloid lineage as well and term this population the primitive common myeloid progenitor (CMP). Treatment of mesoderm-specified cells with Wnt3a led to a loss of hematopoietic colony-forming ability while the inhibition of canonical Wnt signaling with DKK1 led to an increase in the number of primitive CMPs. Canonical Wnt signaling also inhibits the expansion and/or survival of primitive erythrocytes and megakaryocytes, but not myeloid cells, derived from this progenitor population. These findings are in contrast to the role of Wnt signaling during mouse ESC differentiation and demonstrate the importance of the human ESC system in studying species-specific differences in development.

Distinct Sources of Hematopoietic Progenitors Emerge before HSCs and Provide Functional Blood Cells in the Mammalian Embryo

“…Similar to the embryo, the first hematopoietic cells that emerge during differentiation of mouse or human ES cells are primitive erythroblasts with associated macrophages and megakaryocytes, including a primitive MEP (Fujimoto et al, 2003; Keller et al, 1993; Klimchenko et al, 2009; Paluru et al, 2014). Definitive hematopoiesis subsequently emerges, but it remains unclear whether this represents the in vitro equivalent of HSC or EMP-derived definitive potential.…”

“…While there is clear evidence that this two-wave model is an oversimplification, the legacy of this model and its nomenclature still influences many interpretations of hematopoietic emergence. Primitive hematopoiesis is not restricted to erythroid cells, but is associated with macrophage and megakaryocyte potential (Palis et al, 1999; Paluru et al, 2014; Tober et al, 2007; Hoeffel et al 2015). Our data have shown further that primitive and EMP-associated macrophage progenitors can be distinguished prospectively by immunophenotype.…”

CRISPR/Cas9-mediated conversion of human platelet alloantigen allotypes

“…24,25 Briefly, cells were cultured in feeder-free conditions before plating on Matrigel for differentiation. The medium and cytokine changes were followed as described with the following modification.…”

“…24,25 The HPCs generated with this method possess erythroid, megakaryocyte, and myeloid multilineage potential, and coexpress the CD41/CD61 GPIIb-IIIa complex, as well as CD235 (glycophorin A). As shown in Figure 3C, HPCs from both iPSC lines express similar levels of CD41 1 and CD235 1 on their surface, demonstrating importantly that the CRISPR-modified cells retained the full ability to differentiate.…”

ELABELA: a novel hormone in cardiac development acting as a new endogenous ligand for the APJ receptor

“…During embryogenesis, six key signaling pathways (Wnt [3], Bmp/Nodal [4], FGF/IGF [5], Notch [6], Hedgehog [7], and Hippo [8]) have been reported to be crucial for embryonic patterning. Chng et al [1] tried to explain ELA's functions in cardiac development by activating APJ receptor.…”