Mirasol-Treated Platelets - (Pathogen Reduction Extended Storage Study)

Inclusion Criteria: * Male or female of age of 18 years or older. * Have thrombocytopenia or expected to develop thrombocytopenia requiring at least 3 platelet transfusions. * Woman of child bearing potential must have a negative serum or urine pregnancy test within 72 hours before randomization. * Subjects must have signed and dated the Informed Consent Form before performing any protocol related procedure. Exclusion Criteria: * History of any hypersensitivity reaction to riboflavin or metabolites. * History of refractoriness to platelet transfusions (defined as 2 successive CCI1hr\<5000) or presence of human leukocyte antigen (HLA) antibodies or positive lymphocytotoxicity or previously documented alloimmunization. * Previous exposure to PRT-treated platelet concentrates. * Active bleeding requiring one or more red cells concentrate transfusions (i.e. grade 3 or 4 bleeding according to the WHO bleeding assessment scale in Appendix 1). * Exposure to an investigational product, within 30 days before randomization. * Splenomegaly (presence of a palpable spleen whose border could be felt more than 4 cm below the costal margin) or splenectomy. * History or diagnosis of Immune/Idiopathic Thrombocytopenic Purpura (ITP), Thrombotic Thrombocytopenia Purpura (TTP), or Haemolytic Uremic Syndrome (HUS). * Use of prohibited medication (see section 5.5). * Pregnant or lactating females. * Any medical condition or treatment that would be expected to compromise the effectiveness of a platelet transfusion or that would interfere with an expected platelet count increment. * Any other medical condition that would compromise the participation of the subject in the study.