The benefits of most first generation stem cell therapies, in which the overwhelming majority of transplanted cells die fairly rapidly, appear to be mediated by the signals briefly generated by those cells. A sizable portion of the signaling between cells is carried by extracellular vesicles such as exosomes, tiny membrane-wrapped packages of molecules. Given these two points, why not skip the cells in favor of delivering exosomes? This is an expanding area of activity in the regenerative medicine community. Some initiatives, such as the one noted here, have advanced to animal studies – human trials will not be so very many years away.
As regenerative research and development evolves away from the standard practice of the stem cell medicine of the past two decades, the future appears to involve a split of the community into two broad paths. The first path is as described above, to isolate the signals that are important in spurring regeneration, and thus gain control over the behavior of native cells. The second is to solve the problem of transplanted cells dying rather than thriving to undertake useful work. Progress is being made on this front in the form
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