What are exosomes and how do they relate to miRNA cancer detection?

Exosomes are tiny membrane-bound vesicles (40–150 nm in diameter) secreted by virtually all cell types, including cancer cells. Cancer cells secrete exosomes at significantly higher rates than normal cells, and these exosomes carry a cargo that includes DNA, RNA, proteins, and — critically — microRNAs. When cancer exosomes are shed into the bloodstream and subsequently filtered into urine, they deliver elevated concentrations of cancer-associated miRNAs. This is one mechanism by which tumor-derived miRNAs appear in urine at detectable levels even in early-stage disease, when the tumor itself is small and confined. The stability of exosome-packaged miRNA also contributes to the specimen stability observed during OncuraKit shipping.