Antioxidant N-acetyl-L-cysteine increases engraftment of human hematopoietic stem cells in immune-deficient mice

Abstract

Immunocompromised mice, such as the nonobese diabetic/severe combined immu-nodeficient (NOD/SCID) mice, have been widely used to examine the self-renewal and differentiation potential of human hematopoietic stem cells (HSCs)in vivo. However, the efficiency of human HSC engraftment remains very low. Here, we report that NOD/ SCID mice had higher levels of reactive oxygen species (ROS) in their bone marrow (BM) than other commonly used mouse strains (C57BL/6 and BALB/C). Treatment with the antioxidant N-acetyl-L-cysteine (NAC) decreasedROS levelsintheBMofNOD/SCID mice. Furthermore, the NAC-treated mice displayed a significant increase in human HSC engraftment and multilineage hematopoi-etic differentiation in the mice. In comparison with the control mice, NAC-treated recipients displayed a 10.8-fold increase in hematopoietic engraftment in the injected tibiae. A beneficial effect of NAC for human hematopoietic engraftment was also observed in an additional immunodeficient mouse strain, namely NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NOD/SCID/γc-/- or NSG). Thus, this study uncovers a previously unappreciated negative effect of ROS on human stem cell engraftment in immunodeficient mice.