Expression profiles and potential roles of microRNAs in erythrocytes during the aging process

Studies have shown that microRNAs (miRNAs) in red blood cells (RBCs) contribute most of the miRNAs in whole blood, and miRNAs in RBCs are closely related to storage lesions in vitro. However, the role of miRNAs in the process of RBC senescence in vivo remains unclear. We conducted a comprehensive miRNA expression analysis of RBCs collected from enriched mature RBCs in five density layers. The results showed that the type and number of RBC miRNAs changed with the aging of RBCs, the expression levels of 10 RBC miRNAs decreased markedly at the early stage of RBC aging and the levels of 5 RBC miRNAs increased significantly at the terminal stage of RBC senescence. The analysis identified 32 miRNAs whose changes in expression levels were correlated with the two selected aging indexes—pyruvate kinase (PK) activity and RBC indices. The differential expression amounts of the two selected miRNAs (miR-22-3p and miR-144-3p) were confirmed by real-time polymerase chain reaction (PCR) analysis. A bioinformatics analysis identified the potential targets and biological functions of these miRNAs. The experiment of miR-22-3p in the human erythroblast cell line K562 confirmed its negative effects on PK levels. Overall, our research demonstrates, for the first time, that changes in the expression levels of miRNAs during the RBC aging process, and RBC miRNAs thus have the potential to serve as markers of RBC aging in vivo. In addition, the expression of miR-22-3p may regulate RBC senescence by inhibiting PK levels.