title: Successful short-term cryopreservation of volume-reduced cord blood units in a cryogenic mechanical freezer: effects on cell recovery, viability, and clonogenic potential.
abstract: BACKGROUND
  Cord blood (CB) units are stored from weeks to years in liquid- or vapor-phase nitrogen until they are used for transplantation. We examined the effects of cryostorage in a mechanical freezer at -150°C on critical quality control variables of CB collections to investigate the possible use of mechanical freezers at -150°C as an alternative to storage in liquid- (or vapor-) phase nitrogen.
  
  
  METHODS
  A total of 105 CB units were thawed and washed at different time intervals (6, 12, 24, and 36 months). For every thawed CB unit, samples were removed and cell enumeration (total nucleated cells [TNCs], mononuclear cells [MNCs], CD34+, CD133+) was performed. In addition, viability was obtained with the use of flow cytometry, and recoveries were calculated. Also, total absolute colony-forming unit counts were performed and progenitor cell recoveries were studied by clonogenic assays.
  
  
  RESULTS
  Significant differences (p < 0.05) were observed in certain variables (TNCs, MNC numbers, viability) when they were examined in relation with time intervals, while others (CD34+, CD133+) were relatively insensitive (p = NS) to the duration of time interval the CB units were kept in cryostorage condition.
  
  
  CONCLUSIONS
  The data presented suggest that cryopreservation of CB units in a mechanical freezer at -150°C may represent an alternative cryostorage condition for CB cryopreservation.
authors.affiliation: Hellenic Cord Blood Bank, Foundation for Biomedical Research, Academy of Athens; Department of Immunology and National Tissue Typing Center, "G. Gennimatas" General Hospital; Department of Microbiology, Medical School, University of Athens, Athens, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Anagnostakis
authors.forename: Andreas C
authors.initials: AC
authors.lastname: Papassavas
authors.forename: Efstathios
authors.initials: E
authors.lastname: Michalopoulos
authors.forename: Theofanis
authors.initials: T
authors.lastname: Chatzistamatiou
authors.forename: Sofia
authors.initials: S
authors.lastname: Andriopoulou
authors.forename: Athanassios
authors.initials: A
authors.lastname: Tsakris
authors.forename: Catherine
authors.initials: C
authors.lastname: Stavropoulos-Giokas
mesh_terms: D001772:Blood Cell Count; D001793:Blood Preservation / Q000295:instrumentation* / Q000379:methods*; D001810:Blood Volume; D002469:Cell Separation / Q000379:methods*; D002470:Cell Survival / Q000502:physiology; D003114:Colony-Forming Units Assay; D015925:Cryopreservation / Q000295:instrumentation* / Q000379:methods*; D005312:Fetal Blood; D005434:Flow Cytometry; D005615:Freezing; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D006801:Humans; D013997:Time Factors