title: Interlaboratory assessment of a novel colony-forming unit assay: a multicenter study by the cellular team of Biomedical Excellence for Safer Transfusion (BEST) collaborative.
abstract: BACKGROUND
  Interlaboratory scoring performances were determined using a traditional 14-day colony-forming unit (CFU) assay and a new 7-day CFU assay.
  
  
  METHODS
  Digital images of colonies were utilized to train personnel at each site. A central laboratory inoculated methylcellulose with progenitors and sent the samples by overnight courier to participating labs for plating.
  
  
  RESULTS
  Colony counts from two digital images showed greater variability by novice counters (coefficients of variation [CV], 18.5 and 23.0%; n = 8) than for experienced staff (CV, 7.3 and 4.8%; n = 5). CFU assays plated immediately, 24 and 48 hours after methylcellulose inoculation displayed 39.5 CFU, 37.1 ± 10.6 (CV, 28%) and 34.8 ± 8.5 (CV, 24%) colonies for the 7-day assay and 39.5 CFU, 39.1 ± 9.9 (CV, 25%) and 37.1 ± 10.6 (CV, 28%) colonies for the 14-day assay, respectively. Overall, no significant differences in colony counts were noted between assays (p = 0.68). Also, no differences in CFU counts were seen when assays were set up immediately, 24 and 48 hours after methylcellulose inoculation (14-day p = 0.695; 7-day p = 0.632).
  
  
  CONCLUSIONS
  Total CFUs obtained in 7- and 14-day CFU assays are comparable and show similar levels of interlaboratory variability. The major source of this variability is due to differences in how CFU plates are scored by individuals at different sites. UCB progenitor cells can be maintained in methylcellulose-based media at room temperature for up to 48 hours prior to transport without a significant loss in CFUs.
authors.affiliation: Puget Sound Blood Center, Seattle, Washington 98104, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Nawrot
authors.forename: David H
authors.initials: DH
authors.lastname: McKenna
authors.forename: Darin
authors.initials: D
authors.lastname: Sumstad
authors.forename: John D
authors.initials: JD
authors.lastname: McMannis
authors.forename: Zbigniew M
authors.initials: ZM
authors.lastname: Szczepiorkowski
authors.forename: Helen
authors.initials: H
authors.lastname: Belfield
authors.forename: Elke
authors.initials: E
authors.lastname: Grassman
authors.forename: Toni
authors.initials: T
authors.lastname: Temples
authors.forename: Deanna
authors.initials: D
authors.lastname: Nielsen
authors.forename: Ning
authors.initials: N
authors.lastname: Yuan
authors.forename: Bert
authors.initials: B
authors.lastname: Wognum
authors.forename: Jo-Anna
authors.initials: JA
authors.lastname: Reems
mesh_terms: D003114:Colony-Forming Units Assay / Q000379:methods*; D006801:Humans; D013997:Time Factors