Molecular characterization of human osteoblast-derived extracellular vesicle mRNA using next-generation sequencing.

Extracellular vesicles (EVs) are membrane-bound intercellular communication vehicles that transport proteins, lipids and nucleic acids with regulatory capacity between cells. RNA profiling using microarrays and sequencing technologies has revolutionized the discovery of EV-RNA content, which is crucial to understand the molecular mechanism of EV function. Recent studies have indicated that EVs are enriched with specific RNAs compared to the originating cells suggestive of an active sorting mechanism. Here, we present the comparative transcriptome analysis of human osteoblasts and their corresponding EVs using next-generation sequencing. We demonstrate that osteoblast-EVs are specifically depleted of cellular mRNAs that encode proteins involved in basic cellular activities, such as cytoskeletal functions, cell survival and apoptosis. In contrast, EVs are significantly enriched with 254 mRNAs that are associated with protein translation and RNA processing. Moreover, mRNAs enriched in EVs encode proteins important for communication with the neighboring cells, in particular with osteoclasts, adipocytes and hematopoietic stem cells. These findings provide the foundation for understanding the molecular mechanism and function of EV-mediated interactions between osteoblasts and the surrounding bone microenvironment.