title: Intra-bone marrow transplantation facilitates pauci-clonal human hematopoietic repopulation of NOD/SCID/beta2m(-/-) mice.
abstract: OBJECTIVE
  Intra-bone marrow transplantation (IBMT) has been shown to improve the limit of detection of primitive human SCID-repopulating cells (SRC) in NOD/SCID mice when compared to intravenous transplantation. We sought to further refine detection of SRC by comparing NOD/SCID mice to the more sensitive NOD/SCID/beta2m(-/-)strain as IBMT recipients of limiting numbers of purified primitive human hematopoietic cells.
  
  
  METHODS
  Purified human Lin(-)CD34(+)CD38- cells at limiting doses were delivered by IBMT into NOD/SCID and NOD/SCID/beta2m(-/-) strains of recipient mice. Six weeks posttransplantation, injected and noninjected bones were analyzed separately for multilineage human hematopoietic chimerism.
  
  
  RESULTS
  NOD/SCID/beta2m(-/-) mice are superior recipients for IBMT and show a trend toward increased levels of human hematopoietic engraftment. In addition, in contrast to NOD/SCID recipients, NOD/SCID/beta2m(-/-) mice were reconstituted with as few as five highly purified cells, indicative of pauci-clonal repopulation. Analysis of injected and noninjected bones demonstrated that engrafting cells were capable of in vivo migration and expansion. Although SRC hematopoietic reconstitution of NOD/SCID mice is commonly lymphoid-dominant, multilineage analysis of separate bone sites following IBMT of purified cells revealed that a subset of mice was repopulated with a myeloid-dominant graft in at least one bone site, revealing that SRC are developmentally heterogeneous among Lin(-)CD34(+)CD38- cells and capable of distinct differentiation potential.
  
  
  CONCLUSIONS
  IBMT into NOD/SCID/beta2m(-/-) mice provides a highly sensitive experimental transplantation assay for the detection of human hematopoietic repopulating cells and demonstrates that Lin(-)CD34(+)CD38- cells are more highly enriched for human SRC than originally predicted.
authors.affiliation: Robarts Research Institute, Stem Cell Biology and Regenerative Medicine, London, Ontario, Canada.
authors.forename: Krysta
authors.initials: K
authors.lastname: Levac
authors.forename: Pablo
authors.initials: P
authors.lastname: Menendez
authors.forename: Mickie
authors.initials: M
authors.lastname: Bhatia
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation / Q000379:methods*; D001861:Bone Regeneration; D001842:Bone and Bones; D019070:Cell Lineage; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D018183:Transplantation Chimera; D014183:Transplantation, Heterologous