title: Effects of retroviral-mediated MDR1 expression on hematopoietic stem cell self-renewal and differentiation in culture.
abstract: Ex vivo expansion of hematopoietic stem cells would be useful for bone marrow transplantation and gene therapy applications. Toward this goal, we have investigated whether retrovirally-transduced murine stem cells could be expanded in culture with hematopoietic cytokines. Bone marrow cells were transduced with retroviral vectors expressing either the human multidrug resistance 1 gene (HaMDR1), a variant of human dihydrofolate reductase (HaDHFR), or both MDR1 and DHFR in an internal ribosomal entry site (IRES)-containing bicistronic vector (HaMID). Cells were then expanded for 15 days in cultures stimulated with interleukin (IL)-3, IL-6, and stem cell factor. When very low marrow volumes were injected into lethally irradiated recipient mice, long-term reconstitution with 100% donor cells was seen in all mice injected with HaMDR1- or HaMID-transduced cells. By contrast, engraftment with HaDHFR- or mock-transduced cells ranged from partial to undetectable despite injection of significantly larger marrow volumes. In addition, mice transplanted with expanded HaMDR1- or HaMID-transduced stem cells developed a myeloproliferative disorder that was characterized by an increase in abnormal peripheral blood leukocytes. These results show that MDR1-transduced stem cells can be expanded in vitro with hematopoietic cytokines, but indicate that an increased stem cell division frequency can lead to stem cell damage.
authors.affiliation: Division of Experimental Hematology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Bunting
authors.forename: J
authors.initials: J
authors.lastname: Galipeau
authors.forename: D
authors.initials: D
authors.lastname: Topham
authors.forename: E
authors.initials: E
authors.lastname: Benaim
authors.forename: B P
authors.initials: BP
authors.lastname: Sorrentino
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D000818:Animals; D000831:Animals, Newborn; D001854:Bone Marrow Cells / Q000166:cytology*; D016026:Bone Marrow Transplantation; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D007962:Leukocytes / Q000166:cytology / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008954:Models, Biological; D012190:Retroviridae; D014162:Transfection / Q000379:methods*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1