title: Maintenance of murine long-term repopulating stem cells in ex vivo culture is affected by modulation of transforming growth factor-beta but not macrophage inflammatory protein-1 alpha activities.
abstract: Transforming growth factor-beta (TGF-beta) and macrophage inflammatory protein-l alpha (MIP-1 alpha) are both well-described inhibitors of committed and multipotential hematopoietic progenitors. The effect of these cytokines; on true stem cell activity in ex vivo culture systems as assayed by murine long-term repopulating activity (LTRA) has not been examined. We studied the stem cell effects of the addition of these cytokines to ex vivo cultures containing interleukin-3 (IL-3), IL-6, and stem cell factor (SCF), using the murine competitive repopulation assay. We also tested the impact of adding an anti-TGF-beta neutralizing antibody, to ask whether abrogation of autocrine/paracrine TGF-beta may protect or enhance the survival of LTRA during ex vivo culture. TGF-beta 1 had significant suppressive effects on both short- and long-term repopulating activities, and anti-TGF-beta antibody had enhancing effects compared with control cultures containing IL-3, IL-6, and SCF alone. MIP-1 alpha had no significant effects on either short- or long-term repopulating ability. These data suggest that abrogation of TGF-beta during suspension culture may allow enhanced survival or even expansion of primitive cells ex vivo, with implications for many applications, including gene therapy.
authors.affiliation: Hematology Branch, National Heart, Lung, and Blood Institute, National Institute of Health, Bethesda, MD 20892, USA.
authors.forename: T
authors.initials: T
authors.lastname: Soma
authors.forename: J M
authors.initials: JM
authors.lastname: Yu
authors.forename: C E
authors.initials: CE
authors.lastname: Dunbar
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D054407:Chemokine CCL4; D003470:Culture Media / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D007377:Interleukin-3 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D008221:Lymphoid Tissue / Q000166:cytology; D019402:Macrophage Inflammatory Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D015846:Monokines / Q000494:pharmacology*; D019089:Stem Cell Factor / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D054407:Chemokine CCL4; D003470:Culture Media; D007377:Interleukin-3; D015850:Interleukin-6; D019402:Macrophage Inflammatory Proteins; D015846:Monokines; D019089:Stem Cell Factor; D016212:Transforming Growth Factor beta