Using proteins secreted by stem cells, researchers may have found a new, less risky way to regenerate bone tissue for people who have suffered major trauma to their limbs. According to findings published in Scientific Reports this week, the technique could one day provide a sustainable source of fresh tissue.

Right now, to stimulate the growth of new bone tissue, scientists have to grind up old bones to extract growth factors and various proteins known as “demineralized bone matrix” (DMB). This requires taking bones of varying quality from donated cadavers, and there’s no guarantee that enough of the necessary protein signals can be produced. "These limitations motivate the need for more consistent and reproducible source material for tissue regeneration," Todd McDevitt of Gladstone Institutes says in a news release. "As a renewable resource that is both scalable and consistent in manufacturing, pluripotent stem cells are an ideal solution." These have the potential to give rise to almost all cells and tissue types found in mammals.

But rather than use the stem cells themselves, McDevitt and colleagues harnessed their regenerative power by extracting the bone-producing growth factors that the cells secrete. These are called embryoid body-derived material (EBM). First, the team treated mouse stem cells with a chemical and grew them in a special medium that coaxed them towards differentiating into early bone cells. Then, they isolated the essential factors produced by the cells -- these factors are the ones that send the signal to regenerate new bone tissue. Afterwards, they placed the proteins into mouse muscle tissue and found that the proteins alone were sufficient for facilitating bone growth.

"This proof-of-principle work establishes a novel bone formation therapy that exploits the regenerative potential of stem cells," McDevitt adds. "With this technique, we can produce new tissue that is completely stem cell-derived.” Compared to DMB, their EBM performed similarly well.