Implanted Bone Cells Assist Bone Healing

A study published in the journal Cell Metabolism reports that researchers have successfully reprogrammed living bone cells to treat large non-healing bone factures. They do this by enhancing the cells capacity to regenerate even in a harmful environment.

According to researchers, the human body can repair bone fractures by itself in most cases. However, the body’s repair capacity is not sufficient where large bone fractures or defects are concerned. These often fail to heal without help.

To support bone regeneration, researchers world-wide have been developing living implants which consist of cells seeded on supporting structures made of biological material.

“Often, only 30 per cent of the implanted bone cells will survive the first days. A major reason is that the blood vessels around the fracture, which deliver oxygen and nutrients to the cells, are also damaged, ” said Professor Geert Carmeliet from the University of Leuven, Belgium. “The ingrowth of new blood vessels into the implant takes time and until then, the cells are out of fuel since oxygen and nutrient supply is insufficient.”

Carmeliet also said that the starved bone cells produce harmful oxygen radicals which disturb the natural balance between antioxidants and oxygen radicals. She added that an excess of these oxygen radicals causes irreversible cell damage.

Seve Stegen, a doctoral student, explains the next step. “Bone cells activate a dual defense mechanism. First, bone cells increase storage of an emergency fuel in the form of glycogen, which is in fact a sugar reservoir. In addition, bone cells start using glutamine—an amino acid—to produce more antioxidants to neutralize the increased production of harmful oxygen radicals. These two adjustments allow bone cells to be self-supporting in terms of energy generation and to protect themselves against an increased level of oxygen radicals. The oxygen sensor PHD2 can be inactivated via genetic engineering, and also by administering therapeutic molecules.”