microRNA profiling of RBC transcriptome during ex vivo storage

Mature human red blood cells (RBCs) are terminally differentiated anuclear cells. While initially thought to lack any nucleic acids, human RBCs are found to contain abundant and diverse species of RNA transcripts with functional relevance. Given the absence of novel transcription, RBCs may provide an interesting cellular context to study RNA metabolism over time. One clinically relevant context is the ex vivo storage of RBCs in blood banks for use in blood transfusion. Some studies have indicated that the transfusion of “old” or aged stored RBCs may be associated with adverse outcomes due to various storage changes termed “storage lesions”. However, other studies do not support these effects, and much remains unknown about the relevant changes associated with RBC storage. Here, we employed the NanoString nCounter assay for global miRNA profiling to comprehensively define the miRNA turnover during ex vivo RBC storage. This profiling demonstrates that the abundance of most RBC miRNAs did not change significantly during the 42 days of refrigerated storage, indicating extremely long decay half-lives. Unexpectedly, miR-720, a cleavage product of tRNAThr, increased dramatically in the first two weeks and persisted during storage. Furthermore, we present evidence for a role of angiogenin in tRNA cleavage to generate miR-720 during RBC storage. The dramatic increase in miR-720 may serve as a new characteristic for storage lesion and may be used to monitor transfused RBCs in clinical patients and athletes performing blood doping. RBC were processed as in the rountine blood bank practice, the RBC RNA were then purifed and interrogated by Nanostring microRNA v2