microRNA expression profiling in Natural Killer exosomes

Natural Killer (NK) cells are important components of the immune system in the defense against tumor transformation. They release exosomes containing proteins and nucleic acids, including microRNAs (miRNAs) that play a role in the anti-tumor NK cell functions since they are able to recognize and kill cancer cells. In this study, we explored the miRNA content of NK exosomes by microarray as compared to their cellular counterpart and we identified a small subset of miRNAs highly expressed in NK exosomes. Exosomes were purified by ultracentrifugation from supernatant of human long-term interleukin-2 activated NK cell cultures. Culture medium was supplemented with exosome-free fetal bovine serum. We collected 7 samples of NK exosomes and 7 samples of NK cells. After total RNA extraction, samples were hybridized on Affymetrix GeneChip miRNA 4.1 array plate.