title: Red blood cell preservation by droplet freezing with polyvinylpyrrolidone or sucrose-dextrose and by bulk freezing with glycerol.
abstract: BACKGROUND
  Red blood cell (RBC) preservation is essential to transfusion medicine. Many blood group reference laboratories need a method to preserve rare blood samples for serologic testing at a later date. This study offers a comparison of three common cryoprotective agents and protocols used today: bulk preservation with glycerol and droplet freezing with sucrose-dextrose (S+D) or polyvinylpyrrolidone (PVP).
  
  
  METHODS
  Human blood from 14 volunteers was collected and frozen at set intervals over 2 weeks with PVP, S+D, or glycerol. The frozen RBCs were later thawed and the percentage of surviving RBCs was determined. Detailed protocols and an instructional video are supplied.
  
  
  RESULTS
  Over a 2-week period, RBCs preserved with glycerol and thawed with a widely used protocol showed a recovery of 41 ± 16% (mean ± standard deviation) while those thawed with a modified glycerol protocol showed a recovery of 76 ± 8%. RBCs preserved by droplet freezing with S+D showed a recovery of 56 ± 11% while those preserved by droplet freezing with PVP showed a recovery of 85 ± 6%. Recovery values were similar with ethylenediaminetetraacetic acid or heparin anticoagulants, differing freezing rates, and varying droplet volumes.
  
  
  CONCLUSIONS
  Droplet freezing with PVP offered the greatest recovery. While bulk freezing with glycerol can also be effective, droplet freezing may be a more convenient method overall. It requires less effort to thaw, needs much less storage room, and allows blood group laboratories to be frugal with thawing rare samples.
authors.affiliation: Department of Transfusion Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Pirmin
authors.initials: P
authors.lastname: Schmid
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Huvard
authors.forename: A Hallie
authors.initials: AH
authors.lastname: Lee-Stroka
authors.forename: Jae Y
authors.initials: JY
authors.lastname: Lee
authors.forename: Karen M
authors.initials: KM
authors.lastname: Byrne
authors.forename: Willy A
authors.initials: WA
authors.lastname: Flegel
mesh_terms: D001793:Blood Preservation / Q000379:methods*; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004912:Erythrocytes / Q000166:cytology*; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D005990:Glycerol / Q000494:pharmacology*; D006801:Humans; D008297:Male; D010952:Plasma Substitutes / Q000494:pharmacology; D011205:Povidone / Q000494:pharmacology*; D013395:Sucrose / Q000494:pharmacology*; D013549:Sweetening Agents / Q000494:pharmacology; D013997:Time Factors
chemical_list: D003451:Cryoprotective Agents; D010952:Plasma Substitutes; D013549:Sweetening Agents; D013395:Sucrose; D011205:Povidone; D005947:Glucose; D005990:Glycerol