Bioengineers grow living bone for facial reconstruction
Staff Writer |
Researchers have engineered living bone tissue to repair bone loss in the jaw, a structure that is typically difficult to restore.
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The team led by researchers from Columbia University, New York, grafted customized implants into pig jaws that resulted in integration and function of the engineered graft into the recipient's own tissue.
The work, supported in part by the National Institute of Biomedical Imaging and Bioengineering (NIBIB), and reported in the June 15, 2016 issue of Science Translational Medicine, suggests that personalized bone grafts for facial reconstruction may be possible in the future.
Birth defects and injuries can cause bone deformities in the head and face that are difficult to repair.
Replacement bones must be perfectly sculpted to satisfactorily match the features of the person's face. Bones of the jaw, in particular, must also be able to withstand a lot of force in order to chew.
Some current treatments replace missing bone with metal, bone putty derived from deceased donors, or grafted bone from elsewhere within a person's own body. While using the patient's own tissue is the safest strategy, sacrificing bone from elsewhere causes a secondary injury.
It also can be difficult to obtain a piece large enough to carve into an exact match. Bone putty can be very useful to fill a gap, but is not structurally stable without reinforcements that doctors must remove in subsequent surgeries.
Researchers have also experimented with implanting synthetic scaffolds that can enhance new bone growth, but these have not always been successful. To date, none of these options is as useful as doctors would like.
Researchers chose pigs to test the new bone reconstruction technique because their jaw anatomy and type of force and movement are similar to that of people - the ultimate beneficiaries of the potential treatment.
They replaced a piece of the pigs' jawbone with cow bone matrix - the material left after removing its resident cells.
This matrix served as a scaffold for the graft. Guided by precise imaging technology, the researchers individually shaped each cow bone scaffold to fit perfectly into the missing jaw-bone region.
Next, the researchers seeded the scaffold with the pig's own stem cells harvested from the animals' fat, and placed the engineered tissue inside a bioreactor to grow for three weeks.
They then implanted the engineered bone grafts into the pigs and monitored the growth for the next six months. Over that time, the transplanted bone seamlessly integrated into the pigs' jaws. The grafts prompted new bone growth and strengthened the bone enough to tolerate forces needed for the pigs to chew.
The researchers found that the engineered implants remodeled like natural bone. The team found that the pig's body reacted to the implant just like its own bone, breaking it down and rebuilding it as needed. ■