Efficacy and Safety of RBCs Derived From Mirasol-treated Whole Blood in Patients Requiring Chronic Transfusion (PRAISE)

Inclusion Criteria: * 1\. Transfusion dependent thalassemia patient with mean 2-4 week transfusion intervals for the prior 6 months. 2\. Age ≥ 12 years. 3\. Negative pregnancy test for women of childbearing potential and agreement to practice a medically acceptable contraception regimen throughout the participation in the clinical trial. Not required if female subjects are not of child-bearing potential (ie, prior to menses onset, surgically sterilized, 1-year postmenopausal). 4\. Signed informed consent from the patient, or if the patient is \< 18 years of age, signed assent from patient and consent from parent/guardian, according to local Institutional Review Board/Ethics Committee (IRB/EC) requirements. Exclusion Criteria: 1. Historical RBC transfusion requirement of more than 250 mL/kg/year. 2. Presence of RBC antibodies that make procurement of compatible RBC units not feasible per the treating physician's clinical judgment for reasonable execution of the study. 3. Prior treatment with pathogen-reduced RBCs with subsequent development of known antibodies to the associated RBCs. 4. Planned treatment requirement of frozen RBC products. 5. Treatment requirements for any medication that is known to cause hemolysis. 6. Receiving cardiac medications for heart failure. 7. Patients anticipated to receive massive transfusion, per the treating physician's clinical judgment. 8. Known HIV infection (defined as HIV RNA positive) with changes to antiviral regimen within the 12 months prior to screening. 9. Acute or chronic medical disorder that, in the opinion of the Investigator, would impair the ability of the patient to receive study treatment. 10. Participation in another clinical study, either concurrently or within the previous 28 days, in which the study drug or device may influence study endpoints or patient safety, according to Investigator discretion. 11. Participation in another clinical study within the past 3 months if investigational RBCs or treatment or drugs were received that are likely to have long term effect on RBCs function. 12. Pregnant or breastfeeding. 13. Planned concurrent treatment with other pathogen reduction treated blood products during participation in this study. 14. Patients who received prior treatment with pathogen-reduced RBCs within the past 120 days. 15. Inability to comply with study procedures and/or follow-up.