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.
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.
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.
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.
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.