Glass May Help Regenerate Damaged Bone

Sufferers from osteoporosis and broken bones may get a boost from a new type of biocompatible glass that shows promise in helping damaged and diseased bone to regenerate.

A team of researchers from Lehigh University (Bethlehem, PA, USA), the University of Alexandria (Egypt), the Instituto Superior Tecnico (Lisbon, Portugal), and other institutions have developed a specially fabricated glass--similar to the spongy interior of bone--that contains interconnected pores that facilitate vascularization. The glass is porous at two scales, containing both nanopores that measure up to 20 nm in diameter and macropores measuring 100 microns or wider. The dual porosity and the pores' interconnectedness enable the glass to form an effective "scaffold” for bone regrowth. This allows the glass to mimic bone's two vital functions, with the nanopores facilitating cell adhesion and crystallization of bone's structural components, and the macropores allowing bone cells to grow inside the glass and form new blood vessels and tissue.

"When you attach the glass to the damaged bone, a layer forms on the surface of the glass that has the same chemical composition as the natural bone,” said Dr. Mohamed Ammar, a dentist and research scientist in the tissue-engineering lab at Alexandria's faculty of dentistry. "The bone cells come to this layer and attach to it, in effect forming a bone matrix around the glass.”

The glass is manufactured in a sol-gel process, a technique that uses relatively low temperatures to prepare glass and inherently promotes nanoporosity. A polymer is added to the solution to achieve interconnected macroporosity. The new material has been successfully tested in laboratory experiments and is now undergoing in vivo tests in Alexandria.

"Thermodynamically, the coexistence of nanopores and macropores is unstable in that the larger pores should absorb the smaller pores,” said team leader Himanshu Jain, Ph.D., director of the Lehigh-based International Materials Institute for New Functionalities in Glass (IMI-NFG), adding that the addition of the polymer caused a phase separation to occur parallel to the sol-to-gel transition, enabling the researchers to overcome the thermodynamic problem.



Related Links:
Lehigh University
University of Alexandria
Instituto Superior Tecnico