Mesenchymal stem cells (MSCs) derived from human embryonic stem cells (ESCs) have been shown to secrete exosomes that are cardioprotective against myocardial ischemia reperfusion injury in a mouse model. To elucidate this cardioprotective mechanism, we have characterized the protein, nucleic acid, and lipid composition of MSC exosomes. Here we describe the isolation and analysis of RNA in MSC exosome. We have previously reported that RNAs in MSC exosome are primarily small RNA molecules of