Exosomes are endosome-derived vesicles between 40-100 nm in diameter that are secreted by most cell types
and can be distinguished from other types of microvesicles released from the cell by a characteristic protein
composition. Furthermore, it is known that exosomes transport mRNAs, microRNAs (miR) and proteins, all of
which can be used to identify the cell from which they are derived and can be exploited for noninvasive
molecular profiling. Differential expression of exosomal miRs between cancer and normal patient samples has
been described previously. In this study we identified various exosome subpopulations by their particular
surface protein topography. Subsequently, we characterized plasma-derived exosomal RNA content of each
subpopulation for their specific association with a cancer phenotype. We have exploited the protein topography
and RNA content of exosomes found in plasma from patients with cancer, benign prostatic hyperplasia (BPH),
and unaffected individuals in order to characterize and identify the exosome subpopulations that are
indicative of a given disease state. We intend to use the various biosignatures of these exosome subpopulations
to develop a diagnostic platform to aid in the screening and diagnosis of various cancers.