Long-term ex vivo maintenance and expansion of transplantable human hematopoietic stem cells.
We have developed a stromal-based in vitro culture system that facilitates ex vivo expansion of transplantable CD34(+) thy-1(+) cells using long-term hematopoietic reconstitution in severe combined immunodeficient-human (SCID-hu) mice as an in vivo assay for transplantable human hematopoietic stem cells (HSCs). The addition of leukemia inhibitory factor (LIF) to purified CD34(+) thy-1(+) cells on AC6.21 stroma, a murine bone marrow-derived stromal cell line, caused expansion of cells with CD34(+) thy-1(+) phenotype. Addition of other cytokines, including interleukin-3 (IL-3), IL-6, granulocyte-macrophage colony-stimulating factor, and stem cell factor, to LIF in the cultures caused a 150-fold expansion of cells retaining the CD34(+) thy-1(+) phenotype. The ex vivo-expanded CD34(+) thy-1(+) cells gave rise to multilineage differentiation, including myeloid, T, and B cells, when transplanted into SCID-hu mice. Both murine LIF (cannot bind to human LIF receptor) and human LIF caused expansion of human CD34(+) thy-1(+) cells in vitro, suggesting action through the murine stroma. Furthermore, another human HSC candidate, CD34(+) CD38(-) cells, shows a similar pattern of proliferative response. This suggests that ex vivo expansion of transplantable human stem cells under this in vitro culture system is a general phenomenon and not just specific for CD34(+) thy-1(+) cells.
Shih
C C
CC
Department of Hematology/Bone Marrow Transplantation, City of Hope National Medical Center, Duarte, CA, USA. cshih@coh.org
Hu
M C
MC
Hu
J
J
Medeiros
J
J
Forman
S J
SJ
D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006131:Growth Inhibitors / Q000494:pharmacology; D019650:Hematopoietic Stem Cell Mobilization; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000494:pharmacology; D051379:Mice; D016513:Mice, SCID
D006131:Growth Inhibitors; D007377:Interleukin-3; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D008222:Lymphokines; D016178:Granulocyte-Macrophage Colony-Stimulating Factor