Exosomes are nano-sized vesicles surrounded by a lipid membrane, which tend to be secreted toward extra-cellular environments. Despite being defined as vesicles involved in excretion of molecular wastes by Rose Johnstone in the 1970s, further studies revealed them to be effective in various biological processes such as cancer development, regulation of the immune system, intercellular communication, stem cell biology, and tissue/organ regeneration. Although many studies dealing with the role of exosomes in stem cell differentiation and the use of exosomes isolated from stem cells for the treatment of several diseases have been published, the involved mechanisms remain largely unknown. Further understanding of these mechanisms, which include the involved cellular pathways, may improve the use of exosomes in diagnostic and treatment methods, especially for those involving stem cells. Here, we describe some recent data describing the action mechanism of stem cell-derived exosomes focusing on the implicated cellular pathways, hoping to provide novel information that will be useful for cell biology scientists working in this field.