title: Human allogeneic stem cell maintenance and differentiation in a long-term multilineage SCID-hu graft.
abstract: The ability to determine the functional capacity of putative human hematopoietic stem cell (HSC) populations requires in vivo assays in which long-term multilineage differentiation can be assessed. We hypothesized that if human fetal bone was transplanted adjacent to a fetal thymus fragment in severe combined immunodeficient (SCID) mice, a conjoint organ might form in which HSC in the human bone marrow (BM) would mimic human multilineage differentiation into progenitor cells, B cells, and myeloid cells; undergo self-renewal; and migrate to and differentiate into T cells within the thymic microenvironment. To test this possibility, SCID mice were transplanted subcutaneously with HLA class I mismatched fetal bone, thymus, and spleen fragments (SCID-hu BTS). We found that the BM of SCID-hu BTS grafts maintained B cells, myeloid cells, CD34+ cells for at least 36 weeks posttransplant. Assayable hematopoietic progenitors colony-forming units-granulocyte-macrophage were present in 100% (66/66) of grafts over a period of 28 weeks. Cells with a HSC phenotype (CD34+Thy-1+Lin-) were maintained for 20 weeks in SCID-hu BTS grafts. These CD34+Thy-1+Lin- cells had potent secondary multilineage reconstituting potential when isolated and injected into a secondary HLA mismatched SCID-hu bone assay and analyzed 8 weeks later. In addition, early progenitors within the BM of SCID-hu BTS grafts were capable of migrating to the human thymus and undergoing differentiation through immature CD4+CD8+ double-positive T cells and produce mature T cells with a CD4+CD8- or CD8+CD4- phenotype that could be detected for at least 36 weeks. Phenotypically defined human fetal liver (FL) and umbilical cord blood (UCB) hematopoietic stem cell populations were injected into irradiated SCID-hu BTS grafts to assess their multilineage repopulating capacity and to assess the ability of the BTS system to provide an environment where multiple lineages might differentiate from a common stem cell pool. Injection of irradiated grafts with FL HSC or UCB HSC cells resulted in donor-derived B cells, myeloid cells, immature and mature T cells, and CD34+ cells in individual grafts when analyzed 8 weeks postreconstitution, further showing the multipotential nature of these stem cell populations. In addition, a strong correlation was observed between maintenance of host graft-derived CD8+ cells and failure of donor stem cell engraftment.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Experimental Cell Therapy Group, SyStemix Inc, Palo Alto, CA 94304, USA.
authors.forename: C C
authors.initials: CC
authors.lastname: Fraser
authors.forename: H
authors.initials: H
authors.lastname: Kaneshima
authors.forename: G
authors.initials: G
authors.lastname: Hansteen
authors.forename: M
authors.initials: M
authors.lastname: Kilpatrick
authors.forename: R
authors.initials: R
authors.lastname: Hoffman
authors.forename: B P
authors.initials: BP
authors.lastname: Chen
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D001854:Bone Marrow Cells; D016025:Bone Transplantation / Q000276:immunology* / Q000473:pathology; D002454:Cell Differentiation; D016332:Fetal Tissue Transplantation / Q000276:immunology / Q000473:pathology; D005434:Flow Cytometry; D006680:HLA Antigens / Q000032:analysis; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D007700:Kinetics; D008214:Lymphocytes / Q000276:immunology*; D051379:Mice; D016513:Mice, SCID; D014183:Transplantation, Heterologous; D014184:Transplantation, Homologous
chemical_list: D015703:Antigens, CD; D006680:HLA Antigens