title: Use of a flexible thiopyrylium photosensitizer and competitive inhibitor for pathogen reduction of viruses and bacteria with retention of red cell storage properties.
abstract: BACKGROUND
  Progress in developing photochemical methods for pathogen reduction of red blood cells (RBCs) has been hampered by hemolysis. A flexible, nucleic acid-intercalating thiopyrylium (TP) dye that is only photochemically active in the bound state and a competitive inhibitor of RBC membrane binding, dipyridamole (DP), was used to reduce photoinduced hemolysis stemming from free- and membrane-bound dye.
  
  
  METHODS
  Oxygenated leukodepleted 20% hct RBC suspensions were deliberately inoculated with virus or bacteria, incubated with 200 micromol per L DP and less than or equal to 100 micromol per L TP, illuminated with 1.1 J/cm(2) of red light, and titered. RBC suspensions containing 200 micromol per L DP and 160 micromol per L TP were identically phototreated, concentrated to 45% hct, and assayed for RBC storage properties.
  
  
  RESULTS
  In RBC suspensions containing DP, TP photoinactivated vesicular stomatitis virus, pseudorabies virus, duck hepatitis B virus, bovine virus diarrhea virus, extracellular human immunodeficiency virus (HIV) to the limit of detection and 6.2 log intracellular HIV. More than 5 log inactivation of 6 bacterial species was demonstrated. DP prevented approximately 30% of TP binding to RBCs. Phototreated RBCs that were subsequently stored for 42 days exhibited acceptable levels of hemolysis, morphology scores, extracellular pH, ATP, glucose utilization rates, and lactate production. Treated samples exhibited substantially increased potassium efflux compared to controls.
  
  
  CONCLUSIONS
  Use of TP photosensitizer and DP enables significant levels of pathogen reduction while retaining most, but not all RBC properties during 42 day storage.
authors.affiliation: American Red Cross Biomedical Services, Holland Laboratory, Blood and Cell Therapy Development, Rockville, Maryland, 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: Louis
authors.initials: L
authors.lastname: Cincotta
authors.forename: Dedeene
authors.initials: D
authors.lastname: Thompson-Montgomery
authors.forename: Helen
authors.initials: H
authors.lastname: Awatefe
mesh_terms: D000814:Aniline Compounds; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D001424:Bacterial Infections / Q000517:prevention & control*; D001793:Blood Preservation / Q000379:methods*; D004910:Erythrocyte Membrane / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects* / Q000382:microbiology / Q000821:virology; D006461:Hemolysis; D006801:Humans; D017319:Photosensitizing Agents; D011714:Pyrans; D014777:Virus Diseases / Q000517:prevention & control*; D014780:Viruses / Q000187:drug effects / Q000254:growth & development
chemical_list: D000814:Aniline Compounds; D017319:Photosensitizing Agents; D011714:Pyrans; C084408:2-methyl-4,6-bis(N,N-dimethylaminophenyl)pyrylium