Autocrine transforming growth factor beta 1 blocks colony formation and progenitor cell generation by hemopoietic stem cells stimulated with steel factor

Stem Cells. 1993 Jul;11(4):336-47. doi: 10.1002/stem.5530110412.


The ability of Steel Factor (SF) to stimulate colony formation and progenitor cell generation by hemopoietic stem cells (HSCs) in vitro in the absence of interleukin 3 (IL-3) was investigated. IL-3 was required for HSC proliferation, and no or restricted proliferation occurred in the presence of SF, IL-6, IL-11, or IL-12 as single factors or in combination. Neutralizing concentrations of anti-transforming growth factor (TGF)-beta 1 antibodies enhanced progenitor cell generation 2-3-fold in the presence of IL-3, but 75 to over 300-fold when cultures contained at least SF in the absence of IL-3. Exogenous TGF-beta 1 fully abrogated the antibody effects. In the presence of antibodies to TGF-beta 1, SF alone stimulated the delayed formation of small blast cell colonies and SF synergized with IL-6, IL-11, or IL-12 to greatly hasten colony formation, enhance colony number and size, and increase colony forming unit-culture (CFU-C) output from suspension cultures of enriched HSC populations. Secondary CFU-C colonies were significantly larger when IL-3 was absent during the suspension culture phase. Single cell and limiting dilution analysis using a homogenous colony forming unit-spleen (CFU-S) day-12 population and an 800-fold enriched long-term repopulating HSC fraction, respectively, indicated that TGF-beta 1 was an autocrine product of these HSC subsets. Addition of nucleosides, insulin, extra glucose, or serum could not replace the effects of the anti-TGF-beta 1 antibody. While these data offer one possible explanation for reports on the inability of SF to stimulate HSC proliferation, they present the basis for a novel model of the regulation of HSC activation wherein: 1) close-range interactions of HSCs with mesenchymal stromal cells do not exclusively determine maintenance of HSC quiescence; 2) competence acquisition by dormant HSCs may involve the down-regulation or inactivation of autocrine TGF-beta 1; and 3) SF may act as a primary growth factor rather than exclusively as a synergistic cytokine.

MeSH terms

  • Animals
  • CHO Cells / metabolism
  • Cell Division / drug effects
  • Colony-Forming Units Assay
  • Cricetinae
  • Culture Media, Serum-Free / pharmacology
  • Erythropoietin / pharmacology
  • Hematopoietic Cell Growth Factors / antagonists & inhibitors*
  • Hematopoietic Cell Growth Factors / pharmacology
  • Hematopoietic Stem Cells / drug effects*
  • Humans
  • Immunoglobulins / immunology
  • Interleukins / pharmacology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred CBA
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / pharmacology
  • Stem Cell Factor
  • Transforming Growth Factor beta / immunology
  • Transforming Growth Factor beta / metabolism
  • Transforming Growth Factor beta / pharmacology*


  • Culture Media, Serum-Free
  • Hematopoietic Cell Growth Factors
  • IgY
  • Immunoglobulins
  • Interleukins
  • Recombinant Proteins
  • Stem Cell Factor
  • Transforming Growth Factor beta
  • Erythropoietin