MicroRNA profiles as quality biomarkers in stored blood components: A narrative review.

Blood component storage remains fundamental to modern transfusion medicine, yet storage-associated lesions compromise the quality and safety of red blood cell (RBC) concentrates, platelet concentrates (PCs) and plasma products. Conventional quality indicators-including pH, haemolysis percentage, lactate levels, and 2,3-diphosphoglycerate (2,3-DPG) concentrations-provide only a partial assessment of the complex biochemical and molecular deterioration occurring during storage. MicroRNAs (miRNAs), small non-coding RNA molecules of 18-25 nucleotides, have emerged as promising molecular biomarkers capable of reflecting the physiological state of stored blood components with high sensitivity and specificity. We examine miRNA dysregulation patterns in stored RBCs-highlighting miR-96, miR-150, miR-451a and let-7b as key indicators-and in stored PCs, where miR-127, miR-320a, miR-326 and miR-223 demonstrate significant storage-dependent expression changes. The role of extracellular vesicle-associated miRNAs in mediating transfusion-related immunomodulation (TRIM) is discussed, alongside the impact of pathogen inactivation technologies on miRNA integrity. Pre-analytical challenges, technological platforms for miRNA detection and the integration of miRNA profiling with multi-omics approaches for comprehensive quality assessment are critically appraised. Despite considerable promise, standardization of protocols, validation in large-scale clinical settings and cost-effectiveness analyses remain necessary before miRNA-based quality assessment can be translated into routine blood bank practice.