Carbon monoxide treatment rescues leukofiltration and preserves storage quality of red blood cell concentrates from sickle cell trait donors

BACKGROUND: Filtration failures in sickle cell trait (SCT, AS) blood donations limit the availability of antigen-matched red blood cell concentrates (RBCCs) for transfusion. Carbon monoxide (CO), by stabilizing hemoglobin in its high-affinity relaxed state, may prevent filter clogging and restore leukofiltration efficiency. However, the storage quality and stability of CO-treated RBCCs remain to be evaluated. STUDY DESIGN AND METHODS: RBCCs from normal (AA) donors and AS donors with prior leukofiltration failure were categorized as AA-NC (untreated AA), AA-CO (CO-treated AA), and AS-CO (CO-treated AS). CO treatment consisted of exposing RBCCs to CO gas under controlled conditions before leukofiltration. Filtration success, hematological parameters, metabolic stability, oxidative stress markers, and hemolysis parameters were analyzed on days 0, 14, 28, and 42. RESULTS: CO treatment reversed filter clogging in AS RBCCs, enabling successful leukofiltration without significant hemolysis. It induced approximately 90% COHb, with a slight increase in MetHb due to the injection technique, which remained stable throughout the 42-day storage period. Hematological and metabolic parameters were preserved across groups. CO also reduced free Hb oxidation in both AA and AS RBCCs and limited storage lesions in AA RBCCs, whereas AS RBCs remained more prone to senescence at the end of storage. DISCUSSION: CO treatment enables successful leukofiltration of previously non-filterable AS RBCCs and helps preserve RBC quality during storage. This strategy could enhance the availability of antigen-matched RBCCs and improve transfusion safety in sickle cell disease.