NAC protects HSPCs from exogenous ROS, but does not rescue transplantation defect in Nrf2^−/− cells. (A) Experimental schema for NAC experiments. (B) Treatment with NAC protects Nrf2^+/+ and Nrf2^−/− HPSCs from induction of ROS. Mice were treated with daily IP injection of NAC (100 μg/kg/d) for 3 weeks and their BM harvested. Cells were labeled with Abs, treated with 50μM H₂O₂ for 30 minutes, and then stained with H₂-CM-DCFDA to measure intracellular ROS. Data are average MFI values in the KSL population (arbitrary units). Three mice were analyzed in each group. (C) Treatment with NAC does not rescue transplantation defect in Nrf2^−/− HPSCs. Mice were treated with NAC for 3 weeks, BM was harvested, and KSL cells were isolated by FACS. KSL cells (500/mouse) were transplanted, along with 250 000 CD45.1 competitor normal BM cells, and injected into lethally irradiated CD45.1 hosts. Peripheral blood was analyzed for donor chimerism at the indicated time points. Data are average peripheral blood engraftments from 5 total recipient mice per genotype. *P = .03 at 20 weeks.