Liver and marrow of adult mdr-1a/1b(-/-) mice show normal generation, function, and multi-tissue trafficking of primitive hematopoietic cells.
OBJECTIVE
Several lines of evidence suggest that expression of two ABC transporters (Abcg2/Bcrp1 and mdr-1a/b) and the related abilities to efflux Hoechst 33342 (Hst) and Rhodamine-123 (Rho) are features of primitive hematopoietic cells in adult bone marrow. Here we sought to determine the phenotypic and hematopoietic properties of the Hst-effluxing "side" population (SP) cells present in the liver of adult normal mice and whether these might be altered in mdr-1a/1b(-)(/-) mice.


METHODS
Single-cell suspensions of liver (and sometimes bone marrow) were stained with Hst, separated into SP and non-SP fractions, and analyzed for hematopoietic cell-surface marker expression and functional activity in standard in vitro and in vivo (transplantation) assays.


RESULTS
SP cells constituted approximately 1-2% of adult liver cell suspensions and were phenotypically and functionally heterogeneous, even within the approximately 20-25% that expressed CD45. The latter included some lineage marker-positive (lin(+)) cells, less than 15% of all in vitro hematopoietic colony-forming cells in the adult liver and more than 90% of cells identified as long-term culture-initiating cells or in vivo repopulating cells. Interestingly, primary mice reconstituted for greater than or equal to 1 year with adult liver SP cells contained derivative primitive hematopoietic cells in their livers. No differences were seen between +/+ and mdr-1a/1b(-)(/-) mice except for a loss of Rho efflux ability by lin(-)mdr-1a/1b(-)(/-) SP cells.


CONCLUSIONS
Adult murine liver contains a spectrum of hematopoietic cells that are phenotypically and functionally similar to those in the marrow and their generation and properties appear unaffected by a lack of mdr-1a/1b.
Uchida
Naoyuki
N
Terry Fox Laboratory, British Columbia Cancer Agency and Department of Medical Genetics, Medicine and Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada.
Leung
Frank Y K
FY
Eaves
Connie J
CJ
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000172:deficiency / Q000378:metabolism*; D000818:Animals; D000943:Antigens, Differentiation / Q000032:analysis; D001562:Benzimidazoles / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D001854:Bone Marrow Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D003114:Colony-Forming Units Assay; D005456:Fluorescent Dyes / Q000378:metabolism; D019450:Genes, MDR; D006410:Hematopoiesis; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000145:classification / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D016513:Mice, SCID; D020112:Rhodamine 123 / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000943:Antigens, Differentiation; D001562:Benzimidazoles; D005456:Fluorescent Dyes; D020112:Rhodamine 123; D014700:Verapamil; C017807:bisbenzimide ethoxide trihydrochloride