Inflammatory conversion of normal hematopoietic stem and progenitor cells by acute myeloid leukemia derived extracellular vesicles in vivo

Inflammation in the bone marrow (BM) microenvironment is a constitutive component of acute myeloid leukemia (AML) pathogenesis. Studies have demonstrated that leukemic blasts propagate acute inflammation in the AML niche. Our recent studies in a congenic AML model suggest residual healthy hematopoietic stem and progenitor cells (HSPCs) participate in the inflammatory crosstalk. However, the underlying mechanism that drives the inflammatory conversion of HSPCs remains unclear. Here, we ask whether AML-derived extracellular vesicles (EV-AML) can convert HSPCs into an inflammatory active state in vivo. Using EV-AML purified from inducible (i)MLL-AF9 AML blasts (AF9-EV-AML), we challenged healthy C57BL/6J mice with serial injections of AF9-EVAML and analyzed HSPCs transcriptome. We show that HSPC transcriptome corroborates the enrichment of inflammatory and innate immune responses in EVAML-challenged BM HSPCs compared to controls. Our findings suggest that AML converts HSPCs into an inflammatory hub via EVAML in the AML niche.