Apoptotic cell-derived exosomes: messages from dying cells

Intercellular communication: dying cells send out messages Dying cells communicate with healthy cells through molecular messages contained in tiny membrane-encapsulated vesicles called exosomes. In a review article, Yong-Joon Chwae from Ajou University School of Medicine in Suwon, South Korea, and colleagues discuss how these 'apoptotic exosomes' play important roles in immune regulation, with implications for various diseases including inflammatory disorders, cancer, neurodegeneration and infection. Researchers have long known that cells undergoing programmed cell death release vesicles that contain cellular debris, but these larger apoptotic bodies were considered mostly a messy byproduct of the dying process. Recent reports have highlighted the existence of much smaller apoptotic exosomes, each containing signals that aid in triggering and modulating immune responses. Manipulation of these exosomes or their signaling pathways could lead to new treatments for diseases linked to faulty intercellular communication and waste disposal. Apoptosis, a type of programmed cell death that plays a key role in both healthy and pathological conditions, releases extracellular vesicles such as apoptotic bodies and microvesicles, but exosome release due to apoptosis is not yet commonly accepted. Here, the reports demonstrating the presence of apoptotic exosomes and their roles in inflammation and immune responses are summarized, together with a general summary of apoptosis and extracellular vesicles. In conclusion, apoptosis is not just a 'silent' type of cell death but an active form of communication from dying cells to live cells through exosomes.