title: Cryopreservation of hematopoietic progenitor cells from apheresis at high cell concentrations does not impair the hematopoietic recovery after transplantation.
abstract: BACKGROUND
  The high number of nuclear cells (NCs) from hematopoietic progenitor cells-apheresis (HPC-A) requires cryopreservation in large volumes or at high NC concentrations. The effect of NC concentration during cryopreservation has yet to be examined.
  
  
  METHODS
  In the experimental arm (n = 610, Protocol B), the first HPC-A sample from the patient was cryopreserved in two cryobags and subsequent collections in one cryobag, resulting in high NC concentrations (>100 x 10(6) NCs/mL) in most cases. The effect of NC concentrations at freezing in NC recovery after thawing and engraftment kinetics was analyzed and compared with a group of HPC-A cryopreserved at standard NC concentrations (n = 455, Protocol A).
  
  
  RESULTS
  The mean (SD) NC concentration at freezing was 78 (28) x 10(6) per mL (median, 82 x 10(6)/mL; range, 12 x 10(6)-156 x 10(6)/mL) and 183 (108) x 10(6) per mL (median, 156 x 10(6)/mL; range, 16 x 10(6)-678 x 10(6)/mL), for HPC-A cryopreserved according to Protocols A and B, respectively. The NC viabilities of the test vials and HPC-A components after thawing were 88 percent versus 85 percent and 85 percent versus 82 percent, and the cloning efficiency was 49 percent versus 33 percent for Protocols A and B, respectively (p < 0.001). Significant differences were not observed in the recovery of NCs. Days to neutrophil and platelet engraftment were not different between patients transplanted in the standard- (n = 143) or high-cell-concentration group (n = 238).
  
  
  CONCLUSIONS
  The cryopreservation of HPC-A at higher than standard NC concentrations has no adverse impact on hematopoietic reconstitution after transplantation.
authors.affiliation: Transfusion Center and Tissue Bank, Cell Therapy Unit, Duran and Reynals Hospital, Barcelona, Spain. gmartinh@iro.es
authors.forename: Gregorio Angel
authors.initials: GA
authors.lastname: Martin-Henao
authors.forename: Carlos
authors.initials: C
authors.lastname: Torrico
authors.forename: Carmen
authors.initials: C
authors.lastname: Azqueta
authors.forename: Begoña
authors.initials: B
authors.lastname: Amill
authors.forename: Sergio
authors.initials: S
authors.lastname: Querol
authors.forename: Juan
authors.initials: J
authors.lastname: Garcia
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001781:Blood Component Removal; D001793:Blood Preservation / Q000379:methods*; D002452:Cell Count; D002470:Cell Survival; D015925:Cryopreservation; D005260:Female; D005615:Freezing; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D008297:Male; D008875:Middle Aged