title: Viability of cryopreserved BM progenitor cells stored for more than a decade.
abstract: BACKGROUND
  PBPC or BM is increasingly being harvested in remission for possible use in the event of relapse. Although the value of this approach has not been demonstrated, the long-term storage of progenitor cell components has become commonplace in many facilities.
  
  
  METHODS
  We used multi-parameter flow cytometry to determine the viability of 11 long-term cryopreserved BM components (mean = 11.8 years) in liquid phase nitrogen. The components, prepared for autotransplantation but deaccessioned after confirming patient death, were carefully thawed, washed, and assayed immediately. The flow cytometry assay was performed according to the ISHAGE protocol, modified by the addition of 7AAD for analysis of progenitor viability (CD45+ CD34+ 7AAD-) and total leukocyte viability (CD45+ 7AAD-). In addition, total viability was assessed by fluorescence microscopy using acridine orange dye exclusion; granulocyte-monocyte colony-forming units (CFU-GM) were measured after 14 days culture.
  
  
  RESULTS
  Leukocyte viability by flow cytometry and fluorescence microscopy agreed well (r2 = 0.55, slope = 0.83, P < 0.0005 by linear regression). CFU-GM did not correlate with CD34% or any of the viability parameters. Compared with short-term stored (mean = 33 days) PBPC assayed at infusion, long-term stored BM had a comparable percentage of CD34+ cells, comparable CFU-GM activity, increased CD34 viability, but decreased total cell viability, the latter most likely due to an increased proportion of differentiated myeloid cells.
  
  
  CONCLUSIONS
  The results indicate that BM products can be cryopreserved for more than a decade without apparent loss of progenitor activity, as measured by these laboratory surrogates. This agrees with clinical anecdotes describing successful engraftment with long-term stored BM, and argues that expiration dates cannot be set for cryopreserved hematopoietic stem-cell components stored in liquid phase nitrogen.
authors: University of Pittsburgh Cancer Institute, 15213, USA.
authors: A D
authors: AD
authors: Donnenberg
authors: E K
authors: EK
authors: Koch
authors: D L
authors: DL
authors: Griffin
authors: H M
authors: HM
authors: Stanczak
authors: J E
authors: JE
authors: Kiss
authors: T M
authors: TM
authors: Carlos
authors: D M
authors: DM
authors: Buchbarker
authors: A M
authors: AM
authors: Yeager
mesh_terms: D018952:Antigens, CD34 / Q000378:metabolism; D002470:Cell Survival; D015925:Cryopreservation; D005434:Flow Cytometry / Q000379:methods; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology; D007962:Leukocytes / Q000166:cytology / Q000276:immunology; D013995:Time
chemical_list: D018952:Antigens, CD34