title: Calcium is a key constituent for maintaining the in vitro properties of platelets suspended in the bicarbonate-containing additive solution M-sol with low plasma levels.
abstract: BACKGROUND
  Commercially available additive solutions (ASs) require 30% to 35% plasma for optimal storage of platelets (PLTs). PLTs suspended in M-sol, a bicarbonate-based experimental platelet additive solution (PAS), maintain in vitro PLT properties during storage with low levels of plasma (< or =5%).
  
  
  METHODS
  Four different formulations of M-sol were prepared at the optimal pH (6.1): M-sol, M-sol without calcium, M-sol without citric acid, and M-sol without calcium and citric acid. Apheresis PLT units (100% plasma) were equally divided into five 50-mL aliquots in PL732 containers, centrifuged, and resuspended to prepare units suspended in the four different PASs (95%) with 5% plasma and 1 unit in 100% plasma. Units (n = 10) were stored under standard conditions and assayed for in vitro properties on Days 1, 5, and 7. The data were analyzed by analysis of variance for repeated measures (n = 10, p < 0.001).
  
  
  RESULTS
  On Day 5 of storage, PLTs suspended in the M-sol formulation containing calcium but lacking citric acid had similar pH, extent of shape change (ESC) values, and percentage of CD62-positive PLTs and greater hypotonic shock response (HSR) and percentage of discoid PLTs compared to those of PLTs suspended in 100% plasma. In contrast, PLTs suspended in the M-sol formulation lacking calcium had lesser ESC values, greater percentage of CD62-positive PLTs, and similar HSR values and percentage of discoid PLTs compared to those of PLTs suspended in 100% plasma on Day 5 (p < 0.001).
  
  
  CONCLUSIONS
  Calcium plays an important role in maintaining CD62-negative PLTs and relatively high ESC in 5% plasma. The removal of citric acid from M-sol may improve PLT storage properties with low plasma levels.
authors.affiliation: American Red Cross, Holland Laboratory, Rockville, Maryland 20855, USA. wagners@usa.redcross.org
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wagner
authors.forename: Andrey
authors.initials: A
authors.lastname: Skripchenko
authors.forename: Andrew
authors.initials: A
authors.lastname: Myrup
authors.forename: Dedeene
authors.initials: D
authors.lastname: Thompson-Montgomery
authors.forename: Helen
authors.initials: H
authors.lastname: Awatefe
authors.forename: Gary
authors.initials: G
authors.lastname: Moroff
mesh_terms: D001792:Blood Platelets / Q000502:physiology*; D001793:Blood Preservation / Q000379:methods*; D002118:Calcium / Q000494:pharmacology*; D006801:Humans; D017693:Sodium Bicarbonate / Q000494:pharmacology*; D013535:Suspensions
chemical_list: D013535:Suspensions; D017693:Sodium Bicarbonate; D002118:Calcium