Gp130-signaling synergizes with FL and TPO for the long-term expansion of cord blood progenitors.
We investigated the effect of a new fusion protein of IL-6 and the soluble IL-6R, H-IL-6, on the long-term ex vivo expansion of hematopoietic progenitors derived from AC133+cord blood cells. H-IL-6, which acts on both IL-6Ralpha-positive and IL-6Ralpha-negative cells, effectively synergized with FL and TPO with or without SCF for the propagation of primitive progenitors. However, IL-6 showed a greater synergistic effect with FL and TPO than H-IL-6 for long-term progenitor propagation. During the first 6 weeks of culture under stroma-free serum-containing conditions, IL-6 induced a 1.96 +/- 0.64-fold higher expansion of nucleated cells, a 2.28 +/- 0.33-fold higher expansion of CD34+ cells and a 2.74 +/- 0. 28-fold higher expansion of CD34+ AC133+ cells than H-IL-6 in combination with FL and TPO. The propagation of week 6 CAFC was up to four-fold higher in the presence of IL-6 than with H-IL-6. While the expansion of CD34+ and CD34+ AC133+ cells dropped after 5-7 weeks in the stroma-free cultures with FL, TPO and H-IL-6, a sustained expansion for 12 weeks was obtained in the presence of FL, TPO and IL-6. Stroma-contact greatly enhanced the progenitor expansion induced by FL and TPO or FL, TPO and H-IL-6 although the highest proliferation was again obtained in the presence of IL-6. In contrast, the presence of SCF resulted in increased differentiation. Since the majority of primitive progenitors are proposed to be IL-6Ralpha-negative, the results suggest that the synergistic effect of IL-6 is mediated by accessory cells, which have been more effectively stimulated by IL-6 than by the fusion peptide, H-IL-6, in this culture system.
Rappold
I
I
MRC Molecular Haematology Unit, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK.
Watt
S M
SM
Kusadasi
N
N
Rose-John
S
S
Hatzfeld
J
J
Ploemacher
R E
RE
D015703:Antigens, CD / Q000502:physiology*; D050822:Cytokine Receptor gp130; D005312:Fetal Blood / Q000166:cytology / Q000187:drug effects*; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D008562:Membrane Glycoproteins / Q000502:physiology*; D008565:Membrane Proteins / Q000494:pharmacology*; D019089:Stem Cell Factor / Q000494:pharmacology; D017154:Stromal Cells / Q000502:physiology; D013926:Thrombopoietin / Q000494:pharmacology*
D015703:Antigens, CD; C494199:IL6ST protein, human; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D019089:Stem Cell Factor; C084881:flt3 ligand protein; D050822:Cytokine Receptor gp130; D013926:Thrombopoietin