ABSTRACT
BACKGROUND: Exosomes have the function of some mesenchymal stem cells. Understanding the substance composition that plays a representative role in mesenchymal stem cell exosomes will provide clues for further exploration of synthetic exosome analogues. OBJECTIVE: To investigate the difference of microRNA expression profiles in exosomes derived from passage 2 and 5 human umbilical cord mesenchymal stem cells (hUC-MSCs). METHODS: Exosomes in the supernatant of passage 2 and 5 hUC-MSCs were extracted by ultra-high speed centrifugation. The established library was sequenced by using high-throughput sequencing technology. Then we analyzed the sequence results so as to understand the microRNA expression between different groups, and finally did a cluster analysis. RESULTS AND CONCLUSION: 427 657 kinds of microRNAs were detected in the exosomes from passage 2 hUC-MSCs, accounting for 68.93% of the total microRNAs detected; and 119283 microRNAs were detected in the exosomes from passage 5 hUC-MSCs, accounting for 19.22% of the total microRNAs detected. There were 73 526 microRNAs shared between the exosomes from passage 2 and passage 5 hUC-MSCs, accounting for 11.85% of the total microRNAs detected. Bioinformatics analysis (cluster analysis) results showed that these miRNAs were likely to be involved in 161 biological processes, including cell repair, immune and anti-aging. The microRNAs in exosomes from passage 2 to passage 5 hUC-MSCs were largely different. Partial miRNAs exhibited significantly reduced copy numbers. The top five microRNAs with a higher amount, including has-miR-146a-5p, has-miR-191-5p, has-miR-493-3p, has-miR-423-5p, and has-miR-134-5p, have the potential to be the component of synthetic exosome analogues.