title: Purified CD34+ Lin- Thy+ stem cells do not contain clonal myeloma cells.
abstract: High-dose therapy with autologous marrow or peripheral blood stem cell (PBSC) rescue has been extensively applied in the treatment of multiple myeloma (MM) patients during the past 10 years resulting in improved event-free and overall survival when compared with standard chemotherapy. However, relapses are common and cure is unlikely in the majority of patients. Because both bone marrow and PBSCs are contaminated with myeloma cells it is conceivable that relapse after autotransplantation originates at least in part from autografted tumor cells. In this study, mobilized PBSCs were examined for the presence of myeloma cells based on immunophenotyping and sensitive polymerase chain reaction (PCR)-based techniques. In addition, CD34+ Lin- Thy+ stem cells were purified from mobilized PBSC harvests of 10 MM patients by sequentially using counterflow elutriation centrifugation, treatment with phenylalanine methylester, and flow sorting, using 5-parameter gating (propidium iodide, forward scatter, side scatter, CD34+ v Lin- and CD34+ v Thy+). Virtually all mobilized unsorted PBSC preparations contained myeloma cells in sufficient quantities (range, < 0.01 to > 10%) potentially causing a disease relapse. Stem cell purification led to an overall enrichment by about 50-fold in all 10 patients; approximately 90% of the final cell population expressed CD34+ Lin- Thy+ with no evidence of myeloma cell contamination based on flow cytometric analysis of CD38bright cells (< 0.1%). Quantitative PCR amplification of patient-specific complementarity determining region III (CDRIII) DNA sequences showed depletion of clonal B cells by 2.7 to 7.3 logs, with the highest log reduction noted in the samples initially containing the most tumor cells. Our results show that purification of CD34+ Lin- Thy+ cells depletes myeloma cells to undetectable levels from up to 10% present in unsorted PBSCs, thus offering a tool to investigate whether MM relapse after autotransplantation can be reduced markedly.
authors.affiliation: Department of Medicine, University of Arkansas for Medical Sciences, Little Rock, CA 72205, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Gazitt
authors.forename: C C
authors.initials: CC
authors.lastname: Reading
authors.forename: R
authors.initials: R
authors.lastname: Hoffman
authors.forename: A
authors.initials: A
authors.lastname: Wickrema
authors.forename: D H
authors.initials: DH
authors.lastname: Vesole
authors.forename: S
authors.initials: S
authors.lastname: Jagannath
authors.forename: J
authors.initials: J
authors.lastname: Condino
authors.forename: B
authors.initials: B
authors.lastname: Lee
authors.forename: B
authors.initials: B
authors.lastname: Barlogie
authors.forename: G
authors.initials: G
authors.lastname: Tricot
mesh_terms: D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D015703:Antigens, CD / Q000032:analysis*; D018952:Antigens, CD34; D000943:Antigens, Differentiation / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D001781:Blood Component Removal; D019002:CD56 Antigen; D002469:Cell Separation / Q000379:methods*; D002498:Centrifugation; D016384:Consensus Sequence; D003377:Countercurrent Distribution; D003520:Cyclophosphamide / Q000494:pharmacology; D017931:DNA Primers; D005240:Feasibility Studies; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006412:Hematopoietic Stem Cells / Q000737:chemistry / Q000187:drug effects; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D016130:Immunophenotyping; D008562:Membrane Glycoproteins; D009101:Multiple Myeloma / Q000473:pathology*; D009699:N-Glycosyl Hydrolases / Q000032:analysis; D014411:Neoplastic Stem Cells / Q000737:chemistry; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D010950:Plasma Cells / Q000737:chemistry; D016133:Polymerase Chain Reaction; D018800:Thy-1 Antigens / Q000032:analysis*
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D019002:CD56 Antigen; D017931:DNA Primers; D007143:Immunoglobulin Heavy Chains; D008562:Membrane Glycoproteins; D018800:Thy-1 Antigens; C034515:phenylalanine methyl ester; D010649:Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003520:Cyclophosphamide; D009699:N-Glycosyl Hydrolases; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1