Exosomes and extracellular vesicles are nanosized, lipid-bound signaling units derived from cells. Exosomes are secreted by virtually every cell in the body, in response to the surrounding environment, in an attempt to bring the environment back to homeostasis.
Each different type of cell secretes an exosome specific to that type of tissue (heart, liver, lung, kidney, cord, placenta, etc.) so it is incredibly important to know which cell the exosomes are sourced from. Exosomes are non-cellular and are defined as ‘packets of information’ that contain proteins, nucleic acids (messenger RNA and micro RNA), bioactive enzymes, immunomodulatory factors, and growth factors.
The exosome is enclosed in a lipid (fat) bilayer membrane that also contains multiple proteins, allowing them to rapidly penetrate and deliver their bioactive cargo. Scientists agree that the most important part of an exosome is the proteins, because it is the proteins that initiate change.