When it comes to repairing bone injuries or defects, some scientists have been experimenting with a bone-forming protein known as bone morphogenetic protein. It does have some limitations, but those could soon be overcome through the use of a new biomaterial.
One of the main problems with bone morphogenetic protein (BMP) is the fact that it not only causes new bone to grow right at the injury site, but also within the surrounding soft tissue. This happens because the protein leaks out of materials such as biodegradable collagen sponges, that are designed to keep it contained at the site.
Led by bioengineer Marian H. Hettiaratchi, researchers at the University of Oregon are instead looking at combining BMP with an alginate gel and – more importantly – microparticles of an existing medically-approved anticoagulant called heparin. The BMP binds with the heparin particles, with the gel giving the combination some substance and thus staying-power.
In lab tests, the material was injected into nanomesh tubes that had already been inserted into injuries in rats' femurs. The results were promising, with up to 50 percent less "abnormal ossification" (unwanted bone growth) than would have been the case with BMP in a sponge.
"The problem with healing large bone defects clinically is that the BMP delivered using collagen sponges results in abnormal bone formation because the drug doesn't stay on the material," says Hettiaratchi. "Our new material retains much more of the BMP, keeping it localized. You don't get bone formation outside the targeted area."
Because heparin does have some side effects, the team is now working on creating a synthetic alternative, designed specifically for use with BMP on bone injuries.
A paper on the research was published this week in the journal Science Advances.
Source: University of Oregon via EurekAlert