Expansion of human NOD/SCID-repopulating cells by stem cell factor, Flk2/Flt3 ligand, thrombopoietin, IL-6, and soluble IL-6 receptor

J Clin Invest. 2000 Apr;105(7):1013-21. doi: 10.1172/JCI8583.


Here, we demonstrate a significant ex vivo expansion of human hematopoietic stem cells capable of repopulating in NOD/SCID mice. Using a combination of stem cell factor (SCF), Flk2/Flt3 ligand (FL), thrombopoietin (TPO), and a complex of IL-6 and soluble IL-6 receptor (IL-6/sIL-6R), we cultured cord blood CD34(+) cells for 7 days and transplanted these cells into NOD/SCID mice. Bone marrow engraftment was judged successful when recipient animals contained measurable numbers of human CD45(+) cells 10-12 weeks after transplantation. When cells were cultured with SCF+FL+TPO+IL-6/sIL-6R, 13 of 16 recipients were successfully engrafted, and CD45(+) cells represented 11.5% of bone marrow cells in engrafted recipients. Cells cultured with a subset of these factors were less efficiently engrafted, both as measured by frequency of successful transplantations and prevalence of CD45(+) cells. In animals receiving cells cultured with all 4 factors, human CD45(+) cells represented various lineages, including a large number of CD34(+) cells. The proportion of CD45(+) cells in recipient marrow was 10 times higher in animals receiving these cultured cells than in those receiving comparable numbers of fresh CD34(+) cells, and the expansion rate was estimated at 4.2-fold by a limiting dilution method. Addition of IL-3 to the cytokine combination abrogated the repopulating ability of the expanded cells. The present study may provide a novel culture method for the expansion of human transplantable hematopoietic stem cells suitable for clinical applications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD34
  • Bone Marrow Transplantation
  • Culture Media, Serum-Free
  • Hematopoiesis / drug effects*
  • Hematopoietic Stem Cells / cytology*
  • Humans
  • Interleukin-3 / pharmacology
  • Interleukin-6 / metabolism*
  • Interleukin-6 / pharmacology
  • Membrane Proteins / metabolism*
  • Membrane Proteins / pharmacology
  • Mice
  • Mice, Inbred NOD
  • Mice, SCID
  • Receptors, Interleukin-6 / metabolism*
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / pharmacology
  • Solubility
  • Stem Cell Factor / metabolism*
  • Stem Cell Factor / pharmacology
  • Thrombopoietin / metabolism*
  • Thrombopoietin / pharmacology
  • Transplantation, Heterologous


  • Antigens, CD34
  • Culture Media, Serum-Free
  • Interleukin-3
  • Interleukin-6
  • Membrane Proteins
  • Receptors, Interleukin-6
  • Recombinant Proteins
  • Stem Cell Factor
  • flt3 ligand protein
  • Thrombopoietin