Recombinant human c-Mpl ligand (thrombopoietin) not only acts on megakaryocyte progenitors, but also on erythroid and multipotential progenitors in vitro

S. Tanimukai, T. Kimura, H. Sakabe, Y. Ohmizono, T. Kato, H. Miyazaki, H. Yamagishi, Y. Sonoda*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)


To determine the hematopoietic actions of recombinant human c-Mpl ligand (thrombopoietin [TPO]), we studied its effects on the proliferation and differentiation of highly purified CD34+ blood progenitors in plasma- containing and serum-free culture. TPO alone promoted the growth of small megakaryocyte colonies (CFU-Meg) in numbers two to three times greater than those produced by interleukin (IL)-3. The combination of TPO and stem cell factor (SCF) exerted a significant synergistic effect on CFU-Meg formation. In the presence of TPO and IL-3 or granulocyte/macrophage-colony stimulating factor (GM-CSF), a significant number of mixed colonies (CFU-Mix) were observed. The combination of TPO and Epo did not increase the number of CFU- Meg, but did support erythroid-burst (BFU-E) and CFU-Mix colony formation. Interestingly, the combination of TPO with cytokines known to have burst- promoting activity (BPA), including IL-3, GM-CSF, IL-9, and SCF, increased the number of BFU-E and CFU-Mix in the presence of Epo. The BPA of TPO was further investigated by delayed addition of Epo on day 6 after incubation with TPO from day 0. None of the BFU-E or CFU-Mix survived, indicating that TPO acted as a costimulant exclusively for Epo. Moreover, a neutralizing anti-human Mpl receptor polyclonal antibody completely abrogated the BPA of TPO, demonstrating that this effect was mediated through the Mpl receptor. Finally, experiments in single-cell clone sorting and serum-free culture clearly demonstrated that a combination of TPO and Epo directly supported BFU-E and CFU-Mix. These results suggest that TPO acts not only in megakaryocytopoiesis but also in the early stage of hematopoiesis.

Original languageEnglish
Pages (from-to)1025-1033
Number of pages9
JournalExperimental Hematology
Issue number10
Publication statusPublished - 1997 Oct 1
Externally publishedYes


  • BFU-E
  • CD34
  • CFU-Meg
  • CFU-Mix
  • TPO

ASJC Scopus subject areas

  • Molecular Biology
  • Hematology
  • Genetics
  • Cell Biology
  • Cancer Research


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