Many stem cell therapies seem to work via cell signaling rather than any other activity of the transplanted cells, the signals spurring native cells to get back to work and regenerate tissues. Knowing this, the logical end goal of research is then a class of therapy that delivers the signal chemicals rather than cells. Progress on this front is really only limited by the present comparatively poor understanding of just which signals are important in various different circumstances:
Scientists have discovered a way to regrow bone tissue using the protein signals produced by stem cells. The new study is the first to extract the necessary bone-producing growth factors from stem cells and to show that these proteins are sufficient to create new bone. Instead of using stem cells themselves, the scientists extracted the proteins that the cells secrete - such as bone morphogenetic protein (BMP) - in order to harness their regenerative power. To do so, the researchers first treated stem cells with a chemical that helped coax them into early bone cells. Next, they mined the essential factors produced by the cells that send the signal to regenerate new tissue. Finally, the researchers delivered these proteins into mouse muscle tissue to facilitate new bone growth.
The stem cell-based approach was as effective as the current standard treatment in terms of the amount of bone created. This current standard method involves grinding up old bones in order to extract the proteins and growth factors needed to stimulate new bone growth - a substance dubbed demineralized bone matrix (DBM). However, this approach has significant restrictions as it relies on bones taken from cadavers, which can be highly variable in terms of tissue quality and how much of the necessary signals they still produce. Moreover, as is the problem in organ donation, cadaver tissue is not always available. "These limitations motivate the need for more consistent and reproducible source material for tissue regeneration. As a renewable resource that is both scalable and consistent in manufacturing, pluripotent stem cells are an ideal solution."