Exosome isolation and exosomal small RNA quantification. (A) Representative histogram of exosome size distribution. (B) Exosomal RNAs determined using the Agilent Small RNA Chip. The small RNAs were dominant in the exosomal RNAs. (C) Exosomal RNAs determined by the Agilent RNA Pico Chip. Exosomal RNA samples A, B and C contained no detectable 18S and 28S rRNAs. Cellular RNA from HEK293 was loaded as positive control for 18S and 28S rRNAs (D) Isolated exosomal RNAs treated either with DNase I or RNase A. (E) Plasma and control small RNAs treated under various conditions.