title: Variable self-renewal of reconstituting stem cells in long-term bone marrow cultures.
abstract: Long-term bone marrow cultures (LTBMC) serve as a valuable in vitro model of the bone marrow microenvironment. The stromal layer supports the growth of immature and mature cell populations through production of colony-stimulating factors and cell:cell interactions. LTBMC are devoid of mature lymphoid cells but contain stem cells capable of restoring lymphoid and myeloid function in suitable recipients. Severe combined immune deficiency (scid) mice provide a useful environment to study lymphocyte development, as their autosomal recessive mutation on chromosome 16 leaves them with a severe deficiency of B and T lymphocytes. To determine the presence of different classes of stem cells in LTBMC, adherent cells from the cultures were grafted into sublethally irradiated scid mice and lineage reconstitution was evaluated 6 weeks to 3 months postengraftment. Self-renewal of donor stem cells was tested by serial transfer of scid bone marrow to donor secondary C.B-17 and scid recipients. Mature lymphoid and myeloid cells were isolated from reconstituted mice and a restriction fragment length polymorphism (RFLP) at the Cmu immunoglobulin locus was used to distinguish donor and host cells. We found that LTBMC contained both long-term and short-term reconstituting stem cells. The long-term stem cells had significant self-renewal potential and fully reconstituted all lineages in both primary and secondary recipients The short-term stem cells produced mostly lymphoid progeny at the time of analysis and their limited self-renewal capacity led to partial reconstitution of only the primary recipients. The short-term reconstituting cells may be lymphoid-restricted stem cells
authors.affiliation: Department of Immunology, University of Toronto, Canada.
authors.forename: M R
authors.initials: MR
authors.lastname: Chaddah
authors.forename: D D
authors.initials: DD
authors.lastname: Wu
authors.forename: R A
authors.initials: RA
authors.lastname: Phillips
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D006410:Hematopoiesis; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D012150:Polymorphism, Restriction Fragment Length; D011828:Radiation Chimera; D013997:Time Factors