Figure 5.

Growth Factor Requirements for Pro-/Pre-HSC Development

(A) E9 pro-HSCs mature into dHSCs in presence of SCF (S), but not IL-3 (I) (1 e.e./recipient; four independent experiments).

(B) E11 type I pre-HSCs respond by maturing into dHSCs in the presence of SCF, but not IL-3. Meanwhile, type II pre-HSCs respond equally well to SCF and IL-3 (left and right, respectively). Transplantations: type I pre-HSCs: 0.2 ee/recipient (left) and type II pre-HSCs: 0.3 ee/recipient (right) (three independent experiments).

(C) Scf expression in the dorsal aorta, as measured by quantitative PCR, increases 2.5-fold between E9.5 and E10.5. Note that cKit expression remains at the same level during this period of time. Expression levels are normalized to Tbp housekeeping gene expression (three independent RNA preparations). Error bars represent SD.

(D) Long-term donor-derived lymphoid and myeloid contribution in recipient blood derived from E9.5 caudal parts. While SCF on its own generates dHSCs with balanced lymphomyeloid differentiation (∼15%–20% of lymphoid cells), IL-3 on its own or in combination with SCF tends to shift balance more toward myeloid differentiation. Each bar represents an individual recipient (two independent experiments).