BRGS^humanmice support engraftment and repopulating capability of human HSCs more efficiently than do BRGS^NODmice. (A) Frequencies of human CD45⁺ cells in the bone marrow of BRG, BRGS^NOD, and BRGS^human recipient mice injected with 5 × 10³ human Lin⁻CD34⁺CD38⁻ cells at 10 to 12 weeks (left panel) and at 20 to 24 weeks (right) after transplantation (n = 5-16 mice per strain). The numbers and horizontal lines indicate mean values. (B) Frequencies of human CD45⁺ cells in the bone marrow of secondary BRGS^NOD recipients injected with 1 × 10⁶ human CD45⁺ cells purified from the bone marrow of primary BRGS^NOD or BRGS^human recipients. The horizontal lines represent mean values. (C) A limiting dilution assay was used to determine the frequencies of repopulating cells of human HSCs in BRGS^human mice (1 in 32 cells) and BRGS^NOD mice (1 in 141 cells). *P < .05, ***P < .001. n.s., not significant.