HUBEC coculture significantly increases the SRC frequency within human BM CD34⁺CD38^– cells. The scatter plot shows the level of human CD45⁺ cell engraftment in NOD/SCID mice at week 8 following transplantation with FACS-sorted BM CD34⁺CD38^– cells or their progeny as indicated. The progeny of 2 × 10⁴ to 4 × 10⁴ BM CD34⁺CD38^– cells cultured × 7 days with HUBECs + GM36SF showed significantly higher levels of human engraftment compared with day-0 BM CD34⁺CD38^– cells at the same dose. As shown at right, the highest human CD45⁺ cell engraftment was observed in mice that received transplants of the progeny of 4 × 10⁴ BM CD34⁺CD38^– cells following noncontact HUBEC cultures + GM36SF. Mice that received transplants of the progeny of BM CD34⁺CD38^– cells cultured with HUBECs + TSF displayed comparable engraftment to noncontact HUBEC + GM36SF cultures. Each circle represents an individual mouse that received a transplant of human BM cells. Values on the Y-axis indicate the percentage of human CD45⁺ cell engraftment within the marrow of individual mice that received NOD/SCID transplants. The cell dosages for each group are shown at top. The mean levels of human CD45⁺ cell engraftment are indicated by horizontal bars for each group.