Drug delivery across intra-and extracellular barriers remains a major bottleneck in the clinical application of siRNA. To overcome these hurdles, siRNAs need to be packaged in nanosized drug carriers. An exciting new research area involves using cell-derived microvesicles (e.g. exosomes) as delivery tool for macromolecular therapeutics. The major objective is to evaluate exosomes and exosome-mimetic nanoparticles for siRNA delivery