Abstract
The tumor microenvironment is a heterogeneous and dynamic network that exists between cancer and stroma, playing a critical role in cancer progression. Certain tumorigenic signals such as microRNAs are derived from the stroma and conveyed to cancer cells (and vice versa) in nanoparticles called exosomes. Their identification and characterization is an important step in better understanding cellular cross talk and its consequences. To this end we describe how to culture primary ex vivo derived fibroblasts from colorectal tissue, isolate their exosomes, extract exosomal RNA and perform microRNA profiling.