title: Viability does not necessarily reflect the hematopoietic progenitor cell potency of a cord blood unit: results of an interlaboratory exercise.
abstract: BACKGROUND
  Clinical transplant outcome with umbilical cord blood (UCB) as source of hematopoietic progenitor cells (HPCs) is, among other factors, determined by the total number of viable nucleated cells and/or CD34+ cells in the unit. Quantitative and qualitative losses by processing and cryopreservation and by thawing and washing before transfusion may occur, however. Another reason for a discrepancy between the number of cells in the unit released by the cord blood bank and found in the transplant center may be technical differences in cell counting methods between the two sites.
  
  
  METHODS
  With the collaborative group for Biomedical Excellence for Safer Transfusion (BEST), an interlaboratory exercise was conducted among nine sites for thawed UCB variables: total nucleated cells, CD34+ cells, viability, and HPC cultures. Three frozen UCB samples were shipped, with instructions for thawing, counting, and HPC plating.
  
  
  RESULTS
  Unexpectedly samples arrived at all nine receiving centers without detectable hematopoietic progenitor colony-forming cells. Nevertheless, wide interlaboratory ranges for viability were obtained. The proportion of viable cells was found higher with manual methods, but all viability assays used in the study overestimated functional progenitor cells.
  
  
  CONCLUSIONS
  The results underscore the complexity of evaluation of frozen-thawed cord blood cells and the need for standardization of assessment.
authors: Leiden Cord Bloodbank, Sanquin, The Netherlands. a.brand@sanquin.nl
authors: Anneke
authors: A
authors: Brand
authors: Hermann
authors: H
authors: Eichler
authors: Zbigniew M
authors: ZM
authors: Szczepiorkowski
authors: John R
authors: JR
authors: Hess
authors: Riitta
authors: R
authors: Kekomaki
authors: David H
authors: DH
authors: McKenna
authors: Derwood
authors: D
authors: Pamphilon
authors: Joanna
authors: J
authors: Reems
authors: Ronald A
authors: RA
authors: Sacher
authors: Tsuneo A
authors: TA
authors: Takahashi
authors: Leo M G
authors: LM
authors: van de Watering
mesh_terms: D018952:Antigens, CD34 / Q000097:blood; D001771:Blood Banks; D001803:Blood Transfusion / Q000379:methods / Q000592:standards; D002452:Cell Count; D002470:Cell Survival / Q000502:physiology; D005312:Fetal Blood / Q000166:cytology* / Q000378:metabolism; D006405:Hematology / Q000379:methods; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D007753:Laboratories / Q000592:standards
chemical_list: D018952:Antigens, CD34