|A material that changes shape when heated could be used to make custom implants. The white bar is 1 cm long.--Courtesy of Melissa Grunlan|
New research hints at a step beyond 3D printing in making customized implants. Researchers are working on a new material that changes shape when heated and could be used to surgically fill gaps in bone.
The most common current method for filling bone in the head, face or jaw is to remove a bone from elsewhere in the body and shape it to fit the bone defect. This method is difficult and can create complications at the site the bone was taken from. Other options are bone putty or cement, but these become brittle when they harden and lack pores to allow new bone cells to move in and rebuild.
"The problem is that the autograft is a rigid material that is very difficult to shape into these irregular defects," Melissa Grunlan, lead author of the study, said in a statement. Grunlan presented her research at the American Chemical Society conference in San Francisco, CA, from Aug. 10 to 14. She is an associate professor in the Department of Biomedical Engineering at Texas A&M University.
To develop a better approach, Grunlan and her colleagues made a shape-memory polymer that can be molded to the shape of a bone defect without being brittle and that supports the growth of new bone tissue.
To make this porous foam, they used an elastic, biodegradable substance that is already used in medical implants. Once it hardens, it looks like a stiff sponge. When heated in warm water above 140 degrees Fahrenheit, it becomes malleable so that a surgeon can shape the softened material to fill a bone defect. Once it cools to body temperature, it hardens into place. The researchers coated it with polydopamine, a sticky material that helps seal it into place by inducing the mineral formation found in bone.
The researchers then tested whether the scaffold could support bone growth by seeding the polymer with human osteoblasts, cells that synthesize bone. After three days, they found about 5 times as many osteoblasts on the coated material than on those without coating. In addition, the osteoblasts produced more of the proteins runX2 and osteopontin, which are associated with bone formation.
"Now we'd like to move this into preclinical and, hopefully, clinical studies," Grunlan concluded.
- here is the release