Analysis of SRC capacity in subpopulations of CD34⁺CD38⁻Lin⁻ cells based on the expression or absence of cell surface CD7 and AC133. (A) Summary of the level of human engraftment in NOD/SCID mice transplanted with AC133⁺ and AC133⁻ subfractions and CD7⁺ and CD7⁻ subfractions isolated from the CD34⁺CD38⁻Lin⁻population of human CB. Eight weeks after transplantation, the presence of human cells in the BM of 22 mice was assessed by extraction and hybridization of DNA using either Southern blot analysis with a human chromosome 17–specific α-satellite probe or multiparameter flow cytometric analysis with the human-specific pan-leukocyte marker CD45. Each symbol represents a single NOD/SCID recipient. (B) Multilineage differentiation of human AC133⁺ + CD34⁺ + CD38⁻Lin⁻cells in NOD/SCID mice. Bone marrow from a representative engrafted mouse transplanted with 10 000 AC133⁺ + CD34⁺ + CD38⁻Lin⁻CB cells was stained with various human-specific mAbs and analyzed by flow cytometry. (I) Histogram of CD45 (pan-leukocyte marker) expression indicates that 65% of the cells present in the murine BM were human. Analysis of lineage markers was done on cells within gate R2 (CD45⁺). Histogram overlay (single line) represents isotype control for nonspecific IgG staining. Expressions of (II) myeloid marker CD33 and mature myeloid marker CD15, (III) pan-B cell markers CD19 and CD20, and (IV) CD38 and immature hematopoietic marker CD34 are shown. Multilineage engraftment shown here was similar to that found in mice transplanted with CD7⁻CD34⁺CD38⁻Lin⁻cells (data not shown).