The impact on short- and long-term repopulating HSCs by feedback-mediated DL1 is predicted and validated. (A) Comparison of day 12 model predictions and experimental expansion outputs from the fed-batch control culture, the DL1 culture, and the IL-6/sIL-6R culture for (i) total cell expansion; (ii) CD34⁺ cell expansion; and (iii) CD34⁺CD90⁺ cell expansion. (Bi) Model predictions of day 12 short-term SRC expansions under each culture condition. (Bii) Model predictions of long-term SRC expansions after 12 and 16 days of culture. (C) Time course of human engraftment after transplantation of day 12–cultured cells into NSG mice. Bone marrow was assessed at 3, 9, 16, and 24 weeks following transplantation with 500 000 cells cultured in the fed-batch control or the fed-batch plus DL1 culture conditions. (D) Quantification of week 16 SRC expansion, based on limiting dilution analysis performed 16 weeks posttransplantation. Cells were cultured for 12 or 16 days in the fed-batch system with or without DL1 before transplantation. Expansions indicated compared cells cultured in vitro with transplantation of the uncultured CD34⁺ cells. (E) Schematic of the combined effect of DL1 and the fed-batch platform on both rapid and sustained human engraftment.