title: Ex vivo expansion of human hematopoietic stem cells.
abstract: There has been great interest in the ex vivo expansion of human long-term repopulating hematopoietic stem cells (LTR-HSCs) for a variety of clinical applications such as umbilical cord blood transplantation. The glucoprotein130 signal, activated by a complex of interleukin 6 (IL-6) and soluble IL-6 receptor (IL-6/sIL-6R), acts dramatically in synergy with the c-Kit or Flk2/Flt3 signal to expand immature human HSCs. We demonstrate a significant ex vivo expansion of human LTR-HSCs capable of repopulating in newly discovered nonobese diabetes/Shi-severe combined immunodeficient (NOD/Shi-SCID) mice. The proportion of human CD45+ cells in recipient marrow was 10 times higher in animals receiving the cultured cells with stem cell factor, Flk2/Flt3 ligand, thrombopoietin, and IL-6/sIL-6R than in those receiving comparable numbers of fresh cord blood CD34+ cells. The expansion rate provided by this combination was estimated to be 4.2-fold by a limiting dilution method. Addition of IL-3 to the culture with the cytokine combination abrogated the repopulating ability of the expanded cells. The culture method with the IL-6/sIL-6R complex and other cytokines may pave the way for ex vivo expansion of human transplantable HSCs suitable for clinical applications.
authors.affiliation: Department of Pediatrics, Graduate School of Medicine, Kyoto University, Japan. tnakaha@kuhp.kyoto-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Nakahata
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods; D002455:Cell Division / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology; D019947:Receptors, Interleukin-6 / Q000378:metabolism
chemical_list: D015850:Interleukin-6; D019947:Receptors, Interleukin-6