title: Enhanced engraftment of human cells in RAG2/gammac double-knockout mice after treatment with CL2MDP liposomes.
abstract: OBJECTIVE
  The ability of human cells to repopulate the bone marrow of nonobese diabetic immunodeficient mice (NOD/SCID) is commonly used as a standard assay to quantify the primitive human hematopoietic stem cell population. We studied the applicability of the immunodeficient RAG2(-/-)gammac(-/-) double-knockout mouse for this purpose.
  
  
  METHODS
  RAG2(-/-)gammac(-/-) mice and NOD/SCID mice were injected intravenously (i.v.) with umbilical cord blood-derived CD34(+) cells and engraftment was quantified by determining the human CD45+ cell chimerism in bone marrow at several time points. RAG2(-/-)gammac(-/-) were pretreated with total-body irradiation and depleted of macrophages in liver, spleen, and bone marrow by i.v. injection of clodronate diphosphonate containing liposomes.
  
  
  RESULTS
  We demonstrated that the frequency of chimerism and the level of engraftment in macrophage-depleted RAG2(-/-)gammac(-/-) largely resemble that in NOD/SCID mice. Also similar is the multilineage differentiation pattern in the two mouse strains at 7 weeks after transplantation, with a prominent outgrowth in RAG2(-/-)gammac(-/-) of CD19+ cells (88% +/- 10%). Cells of other lineages were clearly less frequent: 9% +/- 2% myeloid cells and 0.1% +/- 0.1% erythroid cells. As for immature progenitors, 6% +/- 1% of the human cells express the CD34 antigen and 0.4% +/- 0.1% have the CD34+,CD33,38,71(-) phenotype. The presence of human committed progenitors (i.e., CFU-GM/BFU-E) was evident. The persistence of human cells at 4 months after transplantation shows that the RAG2(-/-)gammac(-/-) support long-term maintenance of human hematopoiesis.
  
  
  CONCLUSIONS
  Our findings indicate that macrophage-depleted RAG2(-/-)gammac(-/-) are a suitable model for studying human hematopoiesis including multipotential stem cells, and long-term repopulation.
authors.affiliation: Department of Haematology, Jordan Laboratory, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Henk
authors.initials: H
authors.lastname: Rozemuller
authors.forename: Shosh
authors.initials: S
authors.lastname: Knaän-Shanzer
authors.forename: Anton
authors.initials: A
authors.lastname: Hagenbeek
authors.forename: Louis
authors.initials: L
authors.lastname: van Bloois
authors.forename: Gert
authors.initials: G
authors.lastname: Storm
authors.forename: Anton C M
authors.initials: AC
authors.lastname: Martens
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D019070:Cell Lineage; D004002:Clodronic Acid / Q000008:administration & dosage / Q000627:therapeutic use*; D036101:Cord Blood Stem Cell Transplantation / Q000379:methods*; D004268:DNA-Binding Proteins / Q000235:genetics*; D006085:Graft Survival; D006801:Humans; D008081:Liposomes / Q000627:therapeutic use; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D018345:Mice, Knockout; D016513:Mice, SCID; D023421:Models, Animal; D039902:Multipotent Stem Cells / Q000166:cytology; D009687:Nuclear Proteins; D018183:Transplantation Chimera; D014183:Transplantation, Heterologous
chemical_list: D004268:DNA-Binding Proteins; D008081:Liposomes; D009687:Nuclear Proteins; C499311:RAG2 protein, human; C499308:Rag2 protein, mouse; C064655:V(D)J recombination activating protein 2; D004002:Clodronic Acid