RNAs from EVs and cells were isolated using miRNeasy Serum/Plasma kit (#217184, Qiagen) and High Pure RNA Isolation Kit (#11828665001, Roche Diagnostics), respectively, according to the manufacturer's protocols. RNA concentration was quantified by Nanodrop spectrometer (ThermoFisher Scientific, USA) at 260 nm. small RNA library was prepared according to the MGIEasy small RNA library preparation kit (#1000005269, China). Briefly, after 3' and 5' adapter ligation, cDNA was synthesized. After PCR amplification, the product was loaded on a 6% TBE PAGE gel and the portion of the gel corresponding to the appropriate size (100-120 bp) was extracted. The purified PCR product was subjected to denaturation and single-strand circularization, followed by enzymatic digestion and cleanup. The purified product was quantified with a Qubit ssDNA assay kit (#Q10212, Invitrogen).