Hematopoietic reconstitution in the SCID-hu mice with 10,000 ex vivo–expanded CD34⁺ thy-1⁺ cells from 5-week cultures. (A) Intrathymic T-cell development of ex vivo–expanded CD34⁺ thy-1⁺ cells. Graft cells were analyzed by flow cytometry for T-cell markers, CD3, CD4, and CD8, and donor marker (HLA-MA2.1–positive). The percentage of T cells expressing detectable levels of donor-specific HLA class I antigen was recorded. (B) B-cell differentiation and (C) myeloid differentiation of ex vivo–expanded CD34⁺ thy-1⁺ cells in implanted human fetal bone fragment. Graft cells were analyzed for B-cell marker CD19 and myeloid marker CD33, and donor marker HLA-MA2.1.