Fig. 5

Potent activity of ARP on progenitor cell expansion and differentiation. (A) Effects on cultured cell viability and proliferation in liquid cultures. Human CD34¹ cells were cultured (10⁵ cells/ml) in 24-well tissue culture plates and grown in IMDM containing 10% autologous plasma and early-acting cytokines: IL-3 (5 ng), IL-6 (50 ng), TPO (10 ng), FLT-3 ligand (FL, 10 ng), to which stem cell factor (SCF, 10 ng) and/or the synthetic AChE-R peptide (ARP, 2 nM) were added. Note that ARP can replace SCF in inducing hematopoietic cell proliferation and that ARP1 SCF exert synergistic effects under prolong culture conditions. Average 6 SD of four experiments. (B-D) Progenitor cell assays. The presence of CFU progenitors was assessed at weekly intervals in secondary colony assays. CD34¹ progenitors were grown in primary liquid cultures as in Fig. 5A for the noted time, plated in colony assays, and counted after 12–14 days. All cultures contained a combination of growth factors (GFC: IL-3, IL-6, TPO, and FL) to which were added ARP and/or SCF, as noted. Note that ARP can replace SCF in proliferating progenitors for MK and GM, but not blast colonies. Nevertheless, ARP and SCF together exert synergistic effects on CFU-blast. Data are averages of four experiments 6 SEM. (E-H) ARP facilitates development of hematon bodies. Shown are representative photographs of the 28-day liquid cultures detailed in Fig. 5A. (E) In the absence of growth factors, sparse hematopoietic cells and many fibroblasts are seen. (F) Either SCF or (H) ARP increases the density of small, round hematopoietic stem cells and sparse MKs (white arrows). (H) GFC 1 ARP facilitate the formation of hematon bodies (insets) without (H) or with SCF (G).