title: Comparative effects of retroviral-mediated gene transfer into primary human stromal cells of Flt3-ligand, interleukin 3 and GM-CSF on production of cord blood progenitor cells in long-term culture.
abstract: The effects of different cytokines on growth of human cord blood CD34 cells was studied by performing long-term culture (LTC) with primary human stromal cells transduced with genes for either Flt3-ligand (L) (human transmembrane, murine soluble or murine membrane-bound forms), human interleukin 3 (IL-3) or human GM-CSF. Molecular analysis of genomic DNA from transduced stromal cells using neo-specific polymerase chain reaction demonstrated gene transfer of G418-selected stromal cell populations. Enzyme-linked immunosorbent assay and biological assays of conditioned media from transduced stromal cells indicated expression and release of soluble cytokines. Numbers of both immature and more mature progenitors (colony-forming unit-granulocyte, erythroid, macrophage, megakaryocyte; CFU-GEMM, BFU-E, CFU-GM) were increased threefold compared to control in the Flt3-L (transmembrane) LTC throughout five weeks of culture. IL-3 and GM-CSF feeders increased progenitor cell output also, but these effects were significantly lower than Flt3-L feeders. The two Flt3-L isoform engineered feeders, Ex6 (soluble isoform) and 5H (membrane-bound isoform), showed a decreased effect compared to the transmembrane Flt3-L feeders and, in particular, Ex6 feeders were similar to control feeders and 5H feeders were comparable to Flt3-L feeders only in the first two weeks of LTC. These results were apparent also by limiting dilution assays that showed a higher frequency of pre-CFU in the transmembrane Flt3-L feeders compared to control and the other cytokine feeders. Exogenous addition of soluble growth factors to suspension cultures without feeder layers, while superior to stromal feeders for short-term expansion of early progenitors, were inferior to the long-term maintenance/output on stromal feeders. Pre-CFU analysis supported these data. These results may be of some significance to understanding the actions of Flt3-L on blood cell production.
authors.affiliation: Walther Oncology Center, Indiana University School of Medicine and the Walther Cancer Institute, Indianapolis, Indiana, USA.
authors.forename: A
authors.initials: A
authors.lastname: Balduini
authors.forename: S E
authors.initials: SE
authors.lastname: Braun
authors.forename: K
authors.initials: K
authors.lastname: Cornetta
authors.forename: S
authors.initials: S
authors.lastname: Lyman
authors.forename: H E
authors.initials: HE
authors.lastname: Broxmeyer
mesh_terms: D001854:Bone Marrow Cells / Q000166:cytology; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation; D002478:Cells, Cultured; D005312:Fetal Blood / Q000166:cytology*; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000502:physiology*; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D007377:Interleukin-3 / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D012190:Retroviridae; D017154:Stromal Cells / Q000166:cytology* / Q000502:physiology; D014162:Transfection / Q000379:methods
chemical_list: D007377:Interleukin-3; D008565:Membrane Proteins; D011994:Recombinant Proteins; C084881:flt3 ligand protein; D016178:Granulocyte-Macrophage Colony-Stimulating Factor