title: Ex vivo expansion of megakaryocyte progenitor cells: cord blood versus mobilized peripheral blood.
abstract: Thrombocytopenia is a problematic and potentially fatal occurrence after transplantation of cord blood stem cells. This problem may be alleviated by infusion of megakaryocyte progenitor cells. Here, we compared the ability of hematopoietic progenitor cells obtained from cord blood and expanded in culture to that of mobilized peripheral blood cells. The CD34(+) cells were plated for 10 days in presence of thrombopoietin (TPO) alone and combined with stem cell factor (SCF), Flt3-ligand (FL), interleukin-3 (IL-3), IL-6, and IL-11. Cells were analyzed for the CD41 and CD42b expression and for their ploidy status. Ex vivo produced platelets were enumerated. We show that (1) TPO alone was able to induce differentiation of CD34(+) cells into CD41(+) cells, with limited total leucocyte expansion; (2) the addition of SCF to TPO decreased significantly CD41(+) cell percentage in CB, but not in MPB; and (3) in CB, the addition of FL, IL-6, and IL-11 to TPO increased the leukocyte expansion with differentiation and terminal maturation into MK lineage. In these conditions, high numbers of immature CD34(+)CD41(+) MK progenitor cells were produced. Our results thereby demonstrate a different sensitivity of CB and MPB cells to SCF, with limited CB MK differentiation. This different sensitivity to SCF (produced constitutively by BM stromal cells) could explain the longer delay of platelet recovery after CB transplant. Nevertheless, in CB, the combination of TPO with FL, IL-6, and IL-11 allows generation of a suitable number of immature MK progenitor cells expressing both CD34 and CD41 antigens, which are supposed to be responsible for the platelet recovery after transplantation.
authors.affiliation: Experimental Hematology, Jules Bordet Institute, 1000 Brussels, Belgium. cecile.debruyn@bordet.be
authors.forename: C
authors.initials: C
authors.lastname: De Bruyn
authors.forename: A
authors.initials: A
authors.lastname: Delforge
authors.forename: P
authors.initials: P
authors.lastname: Martiat
authors.forename: D
authors.initials: D
authors.lastname: Bron
mesh_terms: D018952:Antigens, CD34 / Q000096:biosynthesis; D001773:Blood Cells / Q000166:cytology*; D001792:Blood Platelets / Q000166:cytology; D018929:Cell Culture Techniques / Q000379:methods*; D002454:Cell Differentiation; D019070:Cell Lineage; D017690:Cell Transplantation; D004247:DNA / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology*; D005434:Flow Cytometry; D006801:Humans; D017370:Interleukin-11 / Q000378:metabolism; D007377:Interleukin-3 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism; D008533:Megakaryocytes / Q000166:cytology*; D008565:Membrane Proteins / Q000378:metabolism; D010641:Phenotype; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000096:biosynthesis; D040201:Platelet Membrane Glycoprotein IIb / Q000096:biosynthesis; D011003:Ploidies; D019089:Stem Cell Factor / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology*; D013926:Thrombopoietin / Q000378:metabolism; D013997:Time Factors
chemical_list: D018952:Antigens, CD34; D017370:Interleukin-11; D007377:Interleukin-3; D015850:Interleukin-6; D008565:Membrane Proteins; D019038:Platelet Glycoprotein GPIb-IX Complex; D040201:Platelet Membrane Glycoprotein IIb; D019089:Stem Cell Factor; C084881:flt3 ligand protein; D004247:DNA; D013926:Thrombopoietin