title: Controlled-rate versus uncontrolled-rate freezing as predictors for platelet cryopreservation efficacy.
abstract: BACKGROUND
  Cryobiologic variables responsible for cell injuries and freezing techniques applicable in medical cryopractice should be revised and/or reengineered for minimizing cryoinjuries and maximizing cell recovery. In this study, the efficacy of different cryopreservation protocols based on platelet (PLT) recovery was evaluated.
  
  
  METHODS
  PLTs (n = 33) were prepared from whole-blood units. Cell count and viability, PLT morphologic score (PMS), and hypotonic shock response were determined. PLT surface antigens were measured by flow cytometry. Controlled-rate (with compensated fusion heat) and uncontrolled-rate freezing methods combined with 6 percent dimethyl sulfoxide were used.
  
  
  RESULTS
  PLT recovery was superior in the controlled-rate setting (91.0 +/- 5.5 vs. 86.0 +/- 6.5; p < 0.05). PMS was significantly better in controlled-rate freezing (p < 0.01). GPIb/CD42b expression was reduced in both freezing groups versus control. GP140/CD62p expression was significantly (p < 0.05) lower in the controlled-rate group and in both frozen groups was significantly higher than in the control groups.
  
  
  CONCLUSIONS
  The use of strictly equalized (1 degrees C/min) controlled-rate freezing, combined with an intensified cooling rate (2 degrees C/min) during the liquid-to-solid-phase transition period, allows advanced quantitative and qualitative PLT recovery, even though the minor intergroup differences for some variables were observed.
authors.affiliation: Laboratory for Experimental Haematology, Institute for Medical Research, Belgrade, Serbia and Montenegro. belab@imi.bg.ac.yu
authors.forename: Bela
authors.initials: B
authors.lastname: Balint
authors.forename: Dragica
authors.initials: D
authors.lastname: Paunovic
authors.forename: Dusan
authors.initials: D
authors.lastname: Vucetic
authors.forename: Danilo
authors.initials: D
authors.lastname: Vojvodic
authors.forename: Marijana
authors.initials: M
authors.lastname: Petakov
authors.forename: Miroljub
authors.initials: M
authors.lastname: Trkuljic
authors.forename: Nevenka
authors.initials: N
authors.lastname: Stojanovic
mesh_terms: D000328:Adult; D016824:Antigens, Human Platelet / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism; D001793:Blood Preservation / Q000379:methods*; D048430:Cell Shape; D002470:Cell Survival; D015925:Cryopreservation / Q000379:methods*; D005434:Flow Cytometry; D005615:Freezing; D006801:Humans; D008297:Male
chemical_list: D016824:Antigens, Human Platelet