Exosomes are 30-100 nm vesicles full of small RNAs secreted by all cell types. Here is a good video from University of Gothenburg on extraction of exosome.
Alternative way is to use commercial kits like ExoQuick [The link also has relevant citations]
Here is a description of what exosomes do from a 2013 report -
Small non-coding RNAs, such as microRNAs (miRNAs), are involved in diverse processes, including organ development and tissue differentiation. Exosomes are small membrane vesicles (30-100?nm in diameter) produced by numerous cells. Recently, exosomes have been shown to contain miRNAs. However, the small RNAs contained in exosomes are not fully characterized. In a previous study, we found at least two types of salivary exosome that are different in size and have different proteomes. Studies of salivary exosomal small RNAs are limited to miRNAs. In this study, we examined small RNA transcriptomes using next generation sequencing technology to elucidate a full transcriptome set of small RNAs expressed in the two types of salivary exosomes and in whole saliva (WS). Many types of small RNA, such as miRNA, piwi-interacting RNA (piRNA), small nucleolar RNA (snoRNA) and other small RNAs are contained in salivary exosomes and WS. Among these small RNAs we identified novel miRNA candidates.
Other informative places:
Early paper in yeast:
People to follow:
Douglas D. Taylor
H. Valdi and the Swedish group mentioned at the top.
[this list will grow]