Long-term ex vivo haematopoietic-stem-cell expansion allows nonconditioned transplantation

Nature. 2019 Jul;571(7763):117-121. doi: 10.1038/s41586-019-1244-x. Epub 2019 May 29.


Multipotent self-renewing haematopoietic stem cells (HSCs) regenerate the adult blood system after transplantation1, which is a curative therapy for numerous diseases including immunodeficiencies and leukaemias2. Although substantial effort has been applied to identifying HSC maintenance factors through the characterization of the in vivo bone-marrow HSC microenvironment or niche3-5, stable ex vivo HSC expansion has previously been unattainable6,7. Here we describe the development of a defined, albumin-free culture system that supports the long-term ex vivo expansion of functional mouse HSCs. We used a systematic optimization approach, and found that high levels of thrombopoietin synergize with low levels of stem-cell factor and fibronectin to sustain HSC self-renewal. Serum albumin has long been recognized as a major source of biological contaminants in HSC cultures8; we identify polyvinyl alcohol as a functionally superior replacement for serum albumin that is compatible with good manufacturing practice. These conditions afford between 236- and 899-fold expansions of functional HSCs over 1 month, although analysis of clonally derived cultures suggests that there is considerable heterogeneity in the self-renewal capacity of HSCs ex vivo. Using this system, HSC cultures that are derived from only 50 cells robustly engraft in recipient mice without the normal requirement for toxic pre-conditioning (for example, radiation), which may be relevant for HSC transplantation in humans. These findings therefore have important implications for both basic HSC research and clinical haematology.

MeSH terms

  • Animals
  • Cell Culture Techniques / methods*
  • Cell Proliferation / drug effects
  • Cell Self Renewal / drug effects*
  • Clone Cells / cytology
  • Clone Cells / drug effects
  • Culture Media / chemistry
  • Culture Media / pharmacology
  • Female
  • Fibronectins / pharmacology
  • Hematopoietic Stem Cell Transplantation / methods*
  • Hematopoietic Stem Cells / cytology*
  • Hematopoietic Stem Cells / drug effects
  • Male
  • Mice
  • Polyvinyl Alcohol / pharmacology
  • Serum Albumin
  • Stem Cell Factor / pharmacology
  • Thrombopoietin / pharmacology
  • Time Factors
  • Transplantation Conditioning


  • Culture Media
  • Fibronectins
  • Serum Albumin
  • Stem Cell Factor
  • Polyvinyl Alcohol
  • Thrombopoietin