Different Expression Profiles of Exosomal circRNAs from Apheresis Platelets during Storage

Introduction: Bioactive substances of stored platelets change during the stored periods. Exosomes are reported to be increased during platelet storage. Circular RNAs (circRNAs) are one of the main components in exosomes. It is the purpose of this study to investigate the different expression of exosomal circRNAs during storage. Methods: Apheresis platelets were collected from 7 healthy volunteers and stored in platelet storage bags for 1 day or 5 days. We isolated exosomes by ultracentrifugation and characterized exosomes by transmission electron microscopy, nano-flow cytometry, and Western blot. We conducted microarray analysis to detect changes in the exosomal circRNAs from apheresis platelets during storage, and qRT-PCR to validate their expressions. To analyze the competing endogenous RNA (ceRNA) of circRNAs, microRNAs (miRNAs) targets were predicted based on interactions of circRNAs/miRNAs and miRNAs/mRNAs, using TargetScan and miRanda. A ceRNA network was constructed by Cytoscape. The targeted mRNAs were performed for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analysis by the DAVID. Results: Microarray analysis revealed that 61 differentially expressed circRNAs between day 1 and day 5. Thirty-one circRNAs of these are upregulated, while 30 circRNAs are downregulated. A ceRNA visualized network includes 9 circRNAs, 48 miRNAs, and 117 mRNAs. There were 117 mRNAs enriched in 203 GO terms and 9 KEGG pathways based on the GO and KEGG pathway enrichment analyses. Conclusion: We identified 61 dysregulated exosomal circRNAs from apheresis platelets during storage. The study provided insights into the underlying mechanisms of platelet storage lesion.