title: Avoiding room temperature storage and delayed cryopreservation provide better postthaw potency in hematopoietic progenitor cell grafts.
abstract: BACKGROUND
  Conditions for maintaining hematopoietic progenitor cells (HPCs) before cryopreservation remain controversial. An understanding of the impact of time and temperature during nonfrozen storage can contribute to the maintenance of the quality of products, improving transplantation outcomes. The objective of this study was to determine the influence on cell potency of thawed products from three sources of HPCs after prolonged storage at different temperatures before cryopreservation.
  
  
  METHODS
  Viable cell counts by flow cytometry and colony-forming unit (CFU) recoveries were assessed on cord blood (CB), mobilized peripheral blood stem cell (PBSC), and bone marrow (BM) samples over 72 hours using two different storage conditions, refrigerated (4-8°C) or room temperature (19-22°C). To determine the effects of delayed freezing on progenitor recoveries, paired samples were evaluated before and after cryopreservation.
  
  
  RESULTS
  All samples maintained at refrigerated temperatures resulted in higher recoveries than those at room temperature in all variables assessed. Specifically, when assessing for CFU yields after thawing, the impact of time on BM resulted in a significant loss as soon as 24 hours (n = 10, 36.4 ± 28.0%, p = 0.003). This decrease was also observed for PBSCs and CB but at 48 hours of fresh storage (PBSCs n = 11, 32.7 ± 26.2%, p = 0.006; CB n = 10, 39.6 ± 26.4%, p = 0.001).
  
  
  CONCLUSIONS
  Our data suggest that HPC products are better maintained at refrigerated temperatures before cryopreservation. Delaying cryopreservation should be minimized to avoid significant losses in cell potency.
authors.affiliation: Anthony Nolan Cell Therapy Centre, John van Geest Cancer Research Centre, Nottingham Trent University, Nottingham, UK. Nottingham NG11 8NS, UK. laura.fry@anthonynolan.org
authors.forename: Laura Jayne
authors.initials: LJ
authors.lastname: Fry
authors.forename: Sergio Querol
authors.initials: SQ
authors.lastname: Giner
authors.forename: Susana G
authors.initials: SG
authors.lastname: Gomez
authors.forename: Melanie
authors.initials: M
authors.lastname: Green
authors.forename: Sally
authors.initials: S
authors.lastname: Anderson
authors.forename: Jackie
authors.initials: J
authors.lastname: Horder
authors.forename: Stephanie
authors.initials: S
authors.lastname: McArdle
authors.forename: Robert
authors.initials: R
authors.lastname: Rees
authors.forename: Jose Alejandro
authors.initials: JA
authors.lastname: Madrigal
mesh_terms: D002452:Cell Count; D002470:Cell Survival; D036101:Cord Blood Stem Cell Transplantation; D015925:Cryopreservation; D005434:Flow Cytometry; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells; D006801:Humans; D036102:Peripheral Blood Stem Cell Transplantation; D013696:Temperature; D013997:Time Factors; D014021:Tissue Preservation / Q000379:methods*