Abstract
Reactive oxygen species (ROS) produced in hematopoietic stem cells (HSCs) are involved in the balance between quiescence, self-renewal, proliferation and differentiation processes. However the role of NOX enzymes on the early stages of hematopoietic differentiation is poorly investigated. For that, we used induced pluripotent stem cells (iPSCs) derived from X-linked Chronic Granulomatous Disease (X0CGD) patients with deficiency in NOX2, and AR220CGD patients with deficiency in p22phox subunit which decreases NOX1, NOX2, NOX3 and NOX4 activities. CD34+ hematopoietic progenitors were obtained after 7, 10 and 13 days of iPS/OP9 co-culture differentiation system. Neither NOX expression nor activity was found in Wild-type (WT), X0CGD and AR220CGD iPSCs. Although NOX2 and NOX4 mRNA were found in WT, X0CGD and AR220CGD iPSC-derived CD34+ cells at day 10 and 13 of differentiation, NOX4 protein was the only NOX enzyme expressed in these cells. A NADPH oxidase activity was measured in WT and X0CGD iPSC-derived CD34+ cells but not in AR220CGD iPSC-derived CD34+ cells because of the absence of p22phox, which is essential for the NOX4 activity. The absence of NOX4 activity and the poor NOX-independent ROS production in AR220CGD iPSC-derived CD34+ cells favored the CD34+ cells production but lowered their hematopoietic potential compared to WT and X0CGD iPSC-derived CD34+ cells. In addition we found a large production of primitive AR220CGD iPSC-derived progenitors at day 7 compared to the WT and X0CGD cell types. In conclusion NOX4 is the major NOX enzyme involved in the early stages of hematopoietic differentiation from iPSCs and its activity can modulate the production, the hematopoietic potential and the phenotype of iPSC-derived CD34+.