Keywords: نیتروسیل هموگلوبین; DPPH; 1,1-diphenyl-2-picrylhydrazyl; EPR (ESR); electron paramagnetic (spin) resonance; FCS; fetal calf serum; HbNO; nitrosylhemoglobin; HSCs; human hemopoietic stem cells; HTM; humanized tumor mouse model; ip (iv); injection into peritoneum (vain); NOS;