Severe Combined Immunodeficiency Mice Engrafted With Human T Cells, B Cells, and Myeloid Cells After Transplantation With Human Fetal Bone Marrow or Liver Cells and Implanted With Human Fetal Thymus: A Model for Studying Human Gene Therapy

Abstract

To develop an in vivo model wherein human hematopoiesis occurs, we transplanted severe combined immunodeficiency (SCID) mice with either human fetal bone marrow (HFBM) or human fetal liver (HFL). After transplantation of SCID mice with cultured HFBM (BM-SCID-hu mice) or HFL cells (Liv-SCID-hu mice), significant engraftment of the mouse bone marrow (BM) and population of the peripheral blood with human leukocytes was detected. Human colony-forming unit–granulocyte macrophage and burst forming unit-erythroid were detected in the BM of the BM-SCID-hu and Liv-SCID-hu mice up to 8 months after transplantation. When the HFBM or HFL cells were transduced with a retroviral vector before transplantation, integrated retroviral sequences were detected in human precursor cells present in the SCID mouse BM and in leukocytes circulating in the peripheral blood (PB) up to 7 months after transplantation. The PB of the BM-SCID-hu mice also became populated with human T cells after implantation with human thymic tissue, which provided a human microenvironment wherein human pre-T cells from the BM could mature. When the HFBM was retrovirally transduced before transplantation, integrated retrovirus was detected in sorted CD4+CD8+ double positive and CD4+ single positive cells from the thymic implant and CD4+ cells from the PB. Taken together, these data indicated that the BM of our BM-SCID-hu and Liv-SCID-hu mice became engrafted with retrovirally transduced human hematopoietic precursors that undergo the normal human hematopoietic program and populate the mouse PB with human cells containing integrated retroviral sequences. In addition to being a model for studying in vivo human hematopoiesis, these mice should also prove to be a useful model for investigating in vivo gene therapy using human stem/precursor cells.

Identification of human T‐lymphoid progenitor cells in CD34+CD38low and CD34+CD38+ subsets of human cord blood and bone marrow cells using NOD‐SCID fetal thymus organ cultures

“…Our rationale for using the NOD‐SCID strain was based on accumulating evidence that NOD‐SCID mice are the most sensitive recipients for transplantable human cells with multiple potentials (Cashman et al , 1997; Pflumio et al , 1996) and are particularly suitable for human B‐lymphoid differentiation (Hogan et al , 1997; Pflumio et al , 1996), and may also support T‐cell differentiation in vivo (van der Loo et al , 1998; Yurasov et al , 1997). Furthermore, the successful development of T cells from fetal liver and cord blood progenitors in murine FTOC has been demonstrated.…”

“…In murine thymus, however, cell proliferation was lower than in human FTOC, and the production of single‐positive CD8 + cells was compromised because murine class I molecules are poor effectors of the CD8 selection. Nevertheless, these studies demonstrated that human T‐lymphoid differentiation could proceed in a murine thymic environment in vitro and recent data suggest that this might occur also in vivo in NOD‐SCID recipients (van der Loo et al , 1998; Yurasov et al , 1997). Since active human B lymphopoiesis and myelopoiesis take place in vivo in NOD‐SCID mice (Cashman et al , 1997; Kollmann et al , 1994; Pflumio et al , 1996; Vormoor et al , 1994), and in vitro in the presence of murine stromal feeders (Berardi et al , 1997; Galy et al , 1995a; Rawlings et al , 1997), one can conclude that a murine environment can support the differentiation of primitive human haemopoietic cells in all lymphoid and myeloid pathways at least when cells from a fetal source are used.…”

SCID Mouse Models of Human Stem Cell Engraftment

“…Low levels of human cells were detectable in the marrow or peripheral tissues of the scid mouse hosts [25]. Investigators have used SCID-hu mice as model systems for the study of human stem cell phenotype and differentiation [42][43][44][45][46][47][48][49][50][51][52], human gene therapy protocols [53][54][55], human T-cell differentiation [56], and homing of human myeloma cells to the bone marrow [57]. SCID-hu mice, in combination with cotransplanted thymic fragments, have been used to investigate the primitive hemopoietic stem cell that populates the T-cell lineage [42,58], for studies of human T-cell function [59,60], and for infection of human T cells and thymus with HIV [61,62].…”

Tumor Necrosis Factor Promotes Human T‐Cell Development in Nonobese Diabetic/Severe Combined Immunodeficient Mice

“…Other studies using in vivo models include the SCID‐hu model, in which human CD34 + cells are coimplanted with T cell–depleted human fetal thymus [16]. Hence, both FTOC and SCID‐hu models are based on the availability of a fetal thymic tissue.…”