Research into exosome signaling has grown in recent years. Arguably the bulk of signaling between cells is transported via varieties of extracellular vesicle, collections of molecules packaged within a membrane. Exosomes are one such type of vesicle. An originating cell generates exosomes, releasing them to the environment, and other cells accept them as they arrive. The contents of an accepted exosome then go on to influence cell machinery and activities. The beneficial effects of most stem cell therapies are mediated by signaling rather than by any other actions of the transplanted cells, and thus in principle it should be possible to do away with the cells and base a therapy on the signals alone. In the near term that might be accomplished by harvesting exosomes from cell cultures, while in the long term manufacturing and delivering specific desired signal molecules directly will probably emerge as the dominant approach.
The research noted here is carried out in cell cultures only, but it is an interesting example of the degree of influence over cell behavior that might be obtained through delivery of exosomes. If cells in many tissue types can be encouraged to greater regeneration and