Low input RNA-seq of endothelial cells sorted from tail of zebrafish larvae
To characterize the mechanism by which AML derived  extracellular vesicles(EV) impaired the vascular architecture and function, EV or PBS injected flk:GFP zebrafish larvae were used for sorting endothelial cells and performing RNA-Seq. Vascular niches sustain hematopoietic stem and progenitor cells (HSPC) and are drastically remodeled in myeloid leukemia to support pathological progression. By utilizing the leukemia-xenografted zebrafish model, we identified that myeloid leukemia secreted extracellular vesicles (EVs) to impair HSPC proliferation, survival and differentiation towards lymphoid/erythroid lineages. The leukemia EVs delivered arginase-1 into venous vasculature to deplete L-arginine and cause NOS uncoupling, which catalyzes production of ROS instead of NO. The oxidative stress caused endothelial cell loss, vascular constriction and failure of secreting niche factors and supporting hematopoiesis. Our findings indicate that myeloid leukemia impaired the vascular function of supporting hematopoiesis by delivering arginase in EVs and arginase inhibition has the potential to improve normal hematopoiesis in myeloid leukemia. Overall design: Comparative gene expression profiling analysis of RNA-seq data for endothelial cells sorted from tails of  MV4-11 derived EV or PBS injected flk:GFP zebrafish larvae.