title: In vitro expansion of hematopoietic progenitors and maintenance of stem cells: comparison between FLT3/FLK-2 ligand and KIT ligand.
abstract: The effects of FLT3/FLK-2 ligand (FL) and KIT ligand (KL) on in vitro expansion of hematopoietic stem cells were studied using lineage-negative (Lin-)Sca-1-positive (Sca-1+) c-kit-positive (c-kit+) marrow cells from 5-fluorouracil (5-FU)-treated mice. As single agents, neither FL nor KL could effectively support the proliferation of enriched cells in suspension culture. However, in combination with interleukin-11 (IL-11), both FL and KL enhanced the production of nucleated cells and progenitors. The kinetics of stimulation by FL was different from that by KL in that the maximal expansion by FL of the nucleated cell and progenitor pools required a longer incubation than with KL. We then tested the reconstituting abilities of cells cultured for 1, 2, and 3 weeks by transplanting the expanded Ly5.1 cells together with "compromised" marrow cells into lethally irradiated Ly5.2 mice. Cells that had been expanded with either cytokine combination were able to maintain the reconstituting ability of the original cells. Only cells that had been incubated with KL and IL-11 for 21 days had less reconstituting ability than fresh marrow cells. These results indicate that there can be significant expansion of progenitors in vitro without compromising the reconstituting ability of stem cells. Addition of IL-3 to permissive cytokine combinations significantly reduced the ability of cultured cells to reconstitute the hematopoiesis of irradiated hosts. These observations should provide a basis for a rational approach to designing cytokine combinations for in vitro expansion of hematopoietic stem cells.
authors.affiliation: Department of Medicine, Medical University of South Carolina, Charleston 29401-5799, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Yonemura
authors.forename: H
authors.initials: H
authors.lastname: Ku
authors.forename: S D
authors.initials: SD
authors.lastname: Lyman
authors.forename: M
authors.initials: M
authors.lastname: Ogawa
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000528:radiation effects; D008024:Ligands; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011518:Proto-Oncogene Proteins / Q000494:pharmacology*; D011828:Radiation Chimera; D020794:Receptor Protein-Tyrosine Kinases / Q000494:pharmacology*; D019089:Stem Cell Factor / Q000494:pharmacology*; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D008024:Ligands; D011518:Proto-Oncogene Proteins; D019089:Stem Cell Factor; C497971:Flt3 protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3