Novel tissue scaffolds help body grow new bone

In a first, chemical engineers led by an Indian-origin researcher at Massachusetts Institute of Technology (MIT) have devised a new implantable tissue scaffold coated with bone growth factors that are released slowly over a few weeks.

When applied to bone injuries or defects, this coated scaffold induces the body to rapidly form new bone that looks and behaves just like the original tissue.

This type of coated scaffold could offer a dramatic improvement over the current standard for treating bone injuries, which involves transplanting bone from another part of the patient's body - a painful process that does not always supply enough bone, researchers reported.

"Patients with severe bone injuries, people who suffer from congenital bone defects and patients in need of bone augmentation prior to insertion of dental implants could benefit from the new tissue scaffold," said lead author Nisarg Shah.

To achieve this, the MIT team created a very thin, porous scaffold sheet coated with layers of two bone growth factors called platelet-derived growth factor (PDGF) and bone morphogenetic protein 2 (BMP-2).

Using a technique called layer-by-layer assembly, they first coated the sheet with about 40 layers of BMP-2; on top of that are another 40 layers of PDGF.

This allowed PDGF to be released more quickly, along with a more sustained BMP-2 release, mimicking aspects of natural healing.

The researchers tested the scaffold in rats with a skull defect large enough a" 8 millimeters in diameter a" that it could not heal on its own.

The scaffold is biodegradable and breaks down inside the body within a few weeks.

"This is a major advantage for tissue engineering for bones because the release of the signaling proteins has to be slow and it has to be scheduled," added Nicholas Kotov, a professor of chemical engineering at University of Michigan who was not part of the research team.

The paper appeared in the journal Proceedings of the National Academy of Sciences.