Evaluation of self-renewal of human HSCs in the BRGS mouse model. (A) Change in frequency of human CD45⁺ cells after transplantation. The level of human CD45⁺ cells was maintained at a high level until 24 weeks after transplantation (8 weeks, n = 29; 16 weeks, n = 17; and 24 weeks, n = 4). (B) Change in the frequency of human CD33⁺ myeloid cells, B cells, T cells, and NK cells in the BM and spleen during the 24 weeks after transplantation (□: 8 weeks; ■: 16 weeks; and ■: 24 weeks). Note that the B-cell numbers gradually decreased and were compensated for by myeloid, T, and NK cells. (C) To test the self-renewal ability of human HSCs maintained in the first recipient mice, 1 × 10⁶ human CD45⁺ cells were sorted from first-recipient mice and injected into second-recipient mice. Only female mice were used as recipients. After another 8 weeks, 4 of 6 BRGS secondary recipients showed multilineage engraftment of human CD33⁺, CD19⁺, and CD3⁺ cells. Representative FACS plots are shown.