title: Long-term cryopreservation of autologous stem cell grafts: a clinical and experimental study of hematopoietic and immunocompetent cells.
abstract: BACKGROUND
  Autologous stem cell transplantation(ASCT) is used in the treatment of several malignancies.Harvesting sufficient peripheral blood progenitor cells (PBPCs) for a potential second autotransplantation at the time of relapse several years after diagnosis is becoming an increasingly common practice.
  
  
  METHODS
  Cryopreserved PBPCs were prepared with different concentrations of dimethyl sulfoxide (DMSO; 2, 4, 5, and 10%) and stored for at least 5 years before the recovery of CD34+ cells and various T- and natural killer (NK)-cell subsets were analyzed by flow cytometry. Furthermore,clinical variables for myeloma patients having a second autotransplantation with long-term-stored autografts were evaluated.
  
  
  RESULTS
  The number of viable CD34+ cells in longterm-stored grafts was higher when autografts were cryopreserved with 4 or 5% than with 2 and 10%DMSO. The number of viable CD34+ cells was reduced by 13.9% after 5 years of cryostorage in 5% DMSO.Lymphocyte viability was also higher with 4 or 5%DMSO. However, the frequencies of several T-cell subsets showed DMSO-dependent differences,whereas NK-cell subsets did not. Furthermore, after a second autotransplantation with long-term-stored PBPC grafts at the time of myeloma relapse (median storage time, 42 months) all 17 patients reached neutrophil counts exceeding 0.5 x 10⁹/L and platelet counts exceeding 20 x 10⁹/L within 15 days. There was no difference in engraftment between patients receiving autografts preserved with 5 and 10% DMSO.
  
  
  CONCLUSIONS
  PBPC autografts can safely be stored for at least 5 years in 5% DMSO and used for ASCT.
authors.affiliation: The Blood Bank, Haukeland University Hospital, Jonas Liesvei 65, N-5021 Bergen, Norway. knut.liseth@haukeland.no
authors.forename: Knut
authors.initials: K
authors.lastname: Liseth
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Ersvær
authors.forename: Jenny Foss
authors.initials: JF
authors.lastname: Abrahamsen
authors.forename: Ingerid
authors.initials: I
authors.lastname: Nesthus
authors.forename: Anita
authors.initials: A
authors.lastname: Ryningen
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Bruserud
mesh_terms: D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D007694:Killer Cells, Natural / Q000166:cytology / Q000378:metabolism; D007958:Leukocyte Count; D008297:Male; D009101:Multiple Myeloma / Q000097:blood / Q000628:therapy*; D036102:Peripheral Blood Stem Cell Transplantation; D020127:Recovery of Function; D012008:Recurrence; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D013997:Time Factors; D014182:Transplantation, Autologous
chemical_list: D003451:Cryoprotective Agents; D004121:Dimethyl Sulfoxide