title: Side-population cells from different precursor compartments.
abstract: The rapid efflux of the fluorescent DNA-binding dye Hoechst 33342 identifies a rare, so-called side population (SP), which rapidly expels the dye, can reconstitute the bone marrow (BM) of lethally irradiated mice, and has proven negative for most lineage markers including CD34. Because SP cells from human cell sources, such as mobilized peripheral blood [apheresis products (AP)], cord blood (CB), or BM have not been extensively characterized to date, we sought to analyze SP cells from various cell sources. We detected murine SP cells with a median frequency of 0.04% (n = 23) and a 52-fold colony-forming units (CFU) increase compared to unsorted cells (p = 0.028). The median frequency of human SP cells was 0.02% (n = 90), with highest numbers in donor AP, and lower in CB and BM. Human SP cells were mostly CD34(-) and lineage marker-negative. These showed no enrichment in CFU before expansion; however, they displayed a CFU increase after 5-7 days of cytokine-supported suspension culture (10.7-fold at day 5, 7.2-fold at day 7; n = 17) that was significant compared to both input (day 0) SP and to non-SP cells before and after expansion (p < 0.05). SP cells demonstrated a significant long-term culture-initiating cell (LTC-IC) increase of 167-fold (n = 17) as compared to non-SP cells (p = 0.002), with the highest numbers from AP specimens. We conclude that human primitive hematopoietic cells can be isolated via Hoechst staining and that SP cells of various human sources show substantial differences and represent a rare CD34(-) population with stem cell potential.
authors.affiliation: University of Freiburg Medical Center, Department of Hematology/Oncology, D-79106 Freiburg, Germany.
authors.forename: Yalin
authors.initials: Y
authors.lastname: Guo
authors.forename: Marie
authors.initials: M
authors.lastname: Follo
authors.forename: Klaus
authors.initials: K
authors.lastname: Geiger
authors.forename: Michael
authors.initials: M
authors.lastname: Lübbert
authors.forename: Monika
authors.initials: M
authors.lastname: Engelhardt
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D018952:Antigens, CD34 / Q000096:biosynthesis / Q000378:metabolism*; D001562:Benzimidazoles / Q000494:pharmacology*; D001781:Blood Component Removal; D001854:Bone Marrow Cells / Q000378:metabolism; D002455:Cell Division; D019070:Cell Lineage; D002469:Cell Separation; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D005312:Fetal Blood / Q000378:metabolism; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D018952:Antigens, CD34; D001562:Benzimidazoles; D016207:Cytokines; D005456:Fluorescent Dyes; C017807:bisbenzimide ethoxide trihydrochloride