To repair a fractured pig tibia, researchers inserted a collagen scaffold that attracts mesenchymal stem cells (MSCs). Two weeks later, they injected a mix of microbubbles and DNA encoding bone morphogenetic protein (BMP) at the fracture site. Finally, they applied a pulse of ultrasound to encourage the MSCs to take up the DNA, and thus begin producing BMP. Within eight weeks, the bones were healed.© GEORGE RETSECK
Repairing limbs after serious injuries can be a challenge for orthopedic surgeons. If the loss of bone is too great, regrowth is impossible. Smaller fractures can also be problematic if bone growth is insufficient because of the advanced age or poor health of the patient.
The gold standard for treating such nonhealing fractures is autologous bone grafts—where a segment of healthy bone (normally harvested from the patient’s pelvis) is used to bridge the wound. But depending on the extent of the damage or the patient’s health, this option is not always feasible. So in recent years, some doctors have begun to administer bone morphogenetic protein (BMP), which is incorporated into a bone implant to boost healing.
This strategy, too, has its pitfalls. “There are significant ...
