title: Hematopoietic stem cells engraft in untreated transplant recipients.
abstract: We investigated the engraftment of hematopoietic stem cells in completely untreated transplant recipients to further study hematopoietic cell regulation and for possible inclusion in gene therapy protocols. Untreated female Balb/c recipients received a single infusion of male Balb/c marrow cells. Donor origin of the hematopoietic cells was determined by polymerase chain reaction (PCR), Southern and in situ hybridization analyses with Y-chromosome-specific probes. We found that up to 47% day 12 CFU-S (26.2 +/- 12.6%, mean +/- SD, range 13.3 to 46.7%), 7.3 +/- 5.5% CFU-GM and from 2.5 to approximately 10% nucleated marrow cells were of donor-origin at 8 weeks after marrow infusion. Our results indicate that hematopoietic stem cells can stably engraft in completely unconditioned recipients but, during the interval analyzed, have a low tendency to differentiate. Moreover, the data suggest that under steady-state conditions, niches for primitive hematopoietic cells present in the marrow microenvironment are not saturated, and are readily available. We conclude that the untreated-recipient transplant model, in conjunction with sensitive techniques for the detection of donor cells, provides a valuable means for studying hematopoietic stem cell regulation and indicates a need to reassess our understanding of the interactions between stem cells and the hematopoietic microenvironment.
authors.affiliation: Toronto Hospital, Ontario, Canada.
authors.forename: D D
authors.initials: DD
authors.lastname: Wu
authors.forename: A
authors.initials: A
authors.lastname: Keating
mesh_terms: D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D016026:Bone Marrow Transplantation; D004247:DNA / Q000235:genetics; D005260:Female; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology*; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D014998:Y Chromosome
chemical_list: D004247:DNA