title: Rhodamine 123 efflux in human subpopulations of hematopoietic stem cells: comparison between bone marrow, umbilical cord blood and mobilized peripheral blood CD34+ cells.
abstract: Hematopoietic stem cells (HSC) can be identified by the expression of the CD34 molecule. CD34+ cells are found in bone marrow (BM), umbilical cord blood (UCB) and in mobilized peripheral blood (PB). CD34+ cells express P-glycoprotein (Pgp), a product of the multidrug resistance (MDR) gene. Pgp activity can be measured by the efflux of the dye Rhodamine 123 (Rho 123) and can be blocked by verapamil. Transport activity in HSC suggests that Pgp could have a functional role in stem cell differentiation. This study compared the number of CD34+ cells with Pgp activity measured by efflux of Rho 123 in the hematopoietic population obtained from different sources. Samples were analysed for their content of CD34+ cells, and BM had a significantly higher amount of CD34+ cells compared to UCB, mobilized PB and normal PB. When the frequency of Rholow cells was studied among the CD34+ population, an enrichment of cells with Pgp activity was observed. The frequency in BM was significantly lower than that in UCB and mobilized PB. The low retention of Rho 123 could be modified by verapamil, indicating that the measurements reflected dye efflux due to Pgp activity. Although UCB and mobilized PB had a lower number of CD34+ cells compared to BM, the total number of CD34+ cells with Pgp activity was similar in the three tissues. The different profiles may indicate the existence of subpopulations of stem cells or different stages of cellular differentiation detected by the extrusion of the dye Rho 123.
authors.affiliation: Laboratório de Imunologia do Centro Nacional de Transplante de Medula óssea, Instituto Nacional de Câncer, CEP RJ, Brazil. kawasoinca@yahoo.com.br
authors.forename: Karen
authors.initials: K
authors.lastname: Wagner-Souza
authors.forename: Hilda Rachel
authors.initials: HR
authors.lastname: Diamond
authors.forename: Maria Helena
authors.initials: MH
authors.lastname: Ornellas
authors.forename: Bernadete Evangelho
authors.initials: BE
authors.lastname: Gomes
authors.forename: Aline
authors.initials: A
authors.lastname: Almeida-Oliveira
authors.forename: Eliana
authors.initials: E
authors.lastname: Abdelhay
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: Bouzas
authors.forename: Vivian Mary
authors.initials: VM
authors.lastname: Rumjanek
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D018952:Antigens, CD34 / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D002454:Cell Differentiation; D002469:Cell Separation; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000378:metabolism*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D016130:Immunophenotyping; D020112:Rhodamine 123 / Q000378:metabolism*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018952:Antigens, CD34; D015415:Biomarkers; D005456:Fluorescent Dyes; D020112:Rhodamine 123