title: Poor stem cell harvest may not always be related to poor mobilization: lessons gained from a mobilization study in patients with β-thalassemia major.
abstract: Hematopoietic stem cell mobilization and leukapheresis in adult patients with β-thalassemia have recently been optimized in the context of clinical trials for obtaining hematopoietic stem cells for thalassemia gene therapy. In some patients, however, the yield of cluster of differentiation 34-positive (CD34+) cells was poor despite successful mobilization, and a modification of apheresis settings was mandatory for harvest rescue.
  
  
  
  Data were analyzed from 20 adult patients with β-thalassemia who were enrolled in a clinical trial of optimizing mobilization strategies for stem cell gene therapy. The aim of this post-hoc analysis was to assess how certain hematological and/or clinical parameters may correlate with low collection efficiency in the presence of adequate numbers of circulating stem cells after pharmacological mobilization and standard leukapheresis procedures.
  
  
  
  Among 19 patients who achieved optimal mobilization with Plerixafor, four who underwent splenectomy demonstrated disproportionately poor CD34+ cell harvests, as determined by their circulating CD34+ cell counts after mobilization. All four patients who underwent splenectomy presented at baseline and before first apheresis with lymphocytosis resulting in lymphocyte/neutrophil ratios well above 1 and marked reticulocytosis compared with patients who achieved optimal mobilization/CD34+ cell harvest. Such unexpected expansion of specific cell populations disrupted the normal cell layer separation and necessitated modification of the apheresis settings to rescue the harvests.
  
  
  
  By close examination of certain hematological and/or clinical parameters before leukapheresis, patients who, despite adequate mobilization, are at risk for poor CD34+ cell harvests may be identified, and harvest failure can be prevented by adjusting the apheresis settings.
authors.affiliation: Gene and Cell Therapy Center, Hematology Department-Bone Marrow Transplant Unit.|Hematology Department-Bone Marrow Transplant Unit, George Papanicolaou Hospital, Thessaloniki, Greece.
authors.forename: Varnavas C
authors.initials: VC
authors.lastname: Constantinou
authors.affiliation: Hematology Department-Bone Marrow Transplant Unit, George Papanicolaou Hospital, Thessaloniki, Greece.
authors.forename: Asimina
authors.initials: A
authors.lastname: Bouinta
authors.affiliation: Gene and Cell Therapy Center, Hematology Department-Bone Marrow Transplant Unit.
authors.forename: Garyfalia
authors.initials: G
authors.lastname: Karponi
authors.affiliation: Gene and Cell Therapy Center, Hematology Department-Bone Marrow Transplant Unit.
authors.forename: Fani
authors.initials: F
authors.lastname: Zervou
authors.affiliation: Gene and Cell Therapy Center, Hematology Department-Bone Marrow Transplant Unit.
authors.forename: Penelope-Georgia
authors.initials: PG
authors.lastname: Papayanni
authors.affiliation: Department of Medicine, University of Washington, Seattle, Washington.
authors.forename: George
authors.initials: G
authors.lastname: Stamatoyannopoulos
authors.affiliation: Gene and Cell Therapy Center, Hematology Department-Bone Marrow Transplant Unit.|Hematology Department-Bone Marrow Transplant Unit, George Papanicolaou Hospital, Thessaloniki, Greece.
authors.forename: Achilles
authors.initials: A
authors.lastname: Anagnostopoulos
authors.affiliation: Gene and Cell Therapy Center, Hematology Department-Bone Marrow Transplant Unit.|Hematology Department-Bone Marrow Transplant Unit, George Papanicolaou Hospital, Thessaloniki, Greece.|Department of Medicine, University of Washington, Seattle, Washington.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Yannaki
mesh_terms: D000328:Adult; D001596:Benzylamines; D000080027:Cyclams; D005260:Female; D015316:Genetic Therapy; D019650:Hematopoietic Stem Cell Mobilization; D006412:Hematopoietic Stem Cells; D006571:Heterocyclic Compounds / Q000008:administration & dosage*; D006801:Humans; D007937:Leukapheresis; D008297:Male; D017086:beta-Thalassemia / Q000097:blood* / Q000235:genetics / Q000628:therapy
chemical_list: D001596:Benzylamines; D000080027:Cyclams; D006571:Heterocyclic Compounds; C088327:plerixafor