Research

Formation of hematopoietic cells from hemogenic precursors on AGM endothelial niche stroma in vitro
Formation of hematopoietic cells from hemogenic precursors on AGM endothelial niche stroma in vitro Credit: Hadland et al. JOVE, In Press, 2018 High-res version

Engineering platforms to recapitulate HSC development ex vivo

We study the vascular microenvironment of the aorta-gonad-mesonephros region (AGM), where HSC first arise in the embryo. We model this niche with AGM-derived endothelial stroma, which provides unique signals sufficient to support HSC generation and self-renewal in vitro.  

Single cell functional and molecular analysis of the dynamics of HSC development from hemogenic endothelium

We use single cell index FACS, with AGM endothelial cell co-culture and transplantation assays, to identify immunophenotypes of functional HSC precursors and assess their clonal lineage potential in vivo. We utilize single cell RNA-sequencing of HSC precursors to identify transcriptional programs regulating HSC development.  Collaborations with members of the UW Genome Science Department, particularly the laboratory of Cole Trapnell, enable us to utilize innovative technologies in single cell omics platforms and computational algorithms to elucidate the dynamic signal pathways regulating HSC development.

Model for vascular niche induction and NOTCH-mediated expansion of HSC's
Model for vascular niche induction and NOTCH-mediated expansion of HSC's Credit: Hadland et al. Journal of Clinical Investigation, 2015 High-res version

Molecular analysis of niche cells supporting HSC development in vivo and in vitro

We use scRNA-seq and multiplexed single molecule RNA fluorescence in situ hybridization to identify intercellular signaling interactions between niche stroma and HSC precursors guiding development of hemogenic endothelium into functional HSC.  We are particularly interested in the how Notch ligand and receptor interactions modulate Notch signal pathway dynamics during HSC development.  We use insight from these studies to model HSC generation in stroma-free systems utilizing Notch receptor agonists and other cooperating niche signals.

Directed differentiation of murine and human pluripotent stem cells to hematopoietic stem and progenitor cells

We apply knowledge gained from studies of HSC development in the embryo model, such as the role of AGM-derived endothelial cell niche signals, to promote generation of multilineage engrafting hematopoietic cells from pluripotent stem cells in vitro.  This work involves local collaboration with the laboratory of Sergei Doulatov in the UW Division of Hematology.

HSC-independent waves of embryonic hematopoiesis
HSC-independent waves of embryonic hematopoiesis Credit: Hadland and Yoshimoto, Experimental Hematology, 2018 High-res version

Development of HSC-independent “innate-like” immune cells during embryonic hematopoiesis

We study the origin of specialized lineages of immune cells that arise uniquely during embryonic development and can contribute to immunity in the adult independently of HSC.  This knowledge may contribute to improving immune reconstitution following hematopoietic stem cell transplantation and to engineering novel cellular immunotherapies.

Mouse AGM Dissection