The proliferation, differentiation and maturation of haematopoietic progenitor cells into megakaryocytic progenitors in vitro, is dependant upon the growth factors. To establish what growth factors give the highest expansion of megakaryocyte progenitors, we developed a culture system differentiating CD34+ haematopoietic stemcells into megakaryocyte progenitors in vitro. This culture system contains a basic growth factor mix (Thrombopoietin (TPO), Granulocyte-Macrophage-Colony Stimulating Factor (GM-CSF), and C-kit-Ligand (CKL,CD117). In addition to this, the cultures were supplemented with foetal calf serum or cultured in a serum-free medium. To further analyse the effect of growth factors on the expansion of megakaryocyte progenitors Flt3/Flk-2 (Flt3) were added in some cases.
The system was used to study the effects of serum-free vs. serum containing medium, and the effect of the growth factor Flt3, on expansion and differentiation of haematopoietic stem cells from human bone marrow, into megakaryocytic progenitors.
Our results demonstrate that serum-free medium is better for culturing haematopoietic and megakaryocytic progenitors, and that Flt3 has a positive effect on the expansion of these cell populations. Serum-containing medium was less able to sustain growth of these progenitors, especially beyond 14 days culture time.