library_construction_protocol: Total RNAs that were extracted from exosomes were pretreated with rtStar tRF & tiRNA Pretreatment Kits to remove RNA modifications that interfere with the construction of small RNA-seq libraries. The cDNA was then synthesized and amplified using Illumina's proprietary RT primers and amplification primers. Subsequently, 134–160-bp PCR-amplified fragments (corresponding to small RNAs that were each 14–40 nt in length) were extracted and purified from an agarose gel.