Dissolving glass may help replace bone transplants

The development may enable patients to re-grow bones and could signal a move away from bone transplants. The porous glass, originally developed at Imperial College in London, is capable of acting as an active template for new bone growth, dissolving in the body without leaving any trace of itself or any toxic chemicals.

Although variants of these bioactive materials are already in clinical use, […] no direct and quantitative study of the calcium atoms within the glass network had been undertaken

Professor Bob Newport

University of Kent

As it dissolves, it releases calcium and other elements such as silicon into the adjacent body fluids, stimulating bone growth.

The glass activates genes present in human bone cells that encode proteins controlling the bone cell cycle and the differentiation of the cell to form bone matrix and rapid mineralisation of bone nodules.

It is the release of soluble silica and calcium ions in specific concentrations that activate the genes. Gene activation occurs only when the timing sequence of the cell cycle is matched by that of the glass surface reactions and controlled release of the ions.

World-leading resources

Partners at the universities of Kent and Warwick have been carrying out experiments at the Science & Technology Facilities Council’s world-leading Isis neutron source. Research at Isis is showing exactly how the calcium is held in the glass and thereby precisely how it is released into the body.

Professor Bob Newport at the University of Kent explains that it was when the material was studied at Isis that the process became clear. He said: “Although variants of these bioactive materials are already in clinical use, and the role of calcium in these materials was already understood as being critical in terms of both the stability of the glass and its bioactivity, no direct and quantitative study of the calcium atoms within the glass network had been undertaken.

We are pleased that at Isis we can continue to contribute to cutting-edge research that affects all our lives

Dr Andrew Taylor

Director of the Isis neutron source

“Using Isis to study the relationship between these atoms and the host silicate glass via techniques unique to neutron diffraction has enabled us to move forward with the programme. The key outcome of our experiments has been a full understanding, at the level of atomic arrangements, of why it is that calcium is able so easily to leave the glass at the rate required to generate the desired response,” he added.

By comparing samples made with natural calcium and with a calcium isotope it was possible for the first time to isolate the complex and subtle contribution of the calcium from that of all the other atoms present.

Cutting-edge research

Dr Andrew Taylor, director of the Isis neutron source, commented: “To allow people to remain active, and to contribute to society for longer, the need for new materials to replace and repair worn-out and damaged tissues becomes ever more important. We are pleased that at Isis we can continue to contribute to cutting-edge research that affects all our lives.

Further research is planned at the Isis second target station when it opens later this year (2008). This will investigate glass/polymer hybrids and could be instrumental in developing mechanically stronger versions of the glass that would be load bearing and available for medical use in the context of joint replacement. If the extensive research goes as expected, clinical trials could be in place in the next five years.

Isis is a world-leading centre for research in physical and life sciences operated by the Science & Technology Facilities Council (STFC) at the Rutherford Appleton Laboratory on the Harwell Science & Innovation Campus in Oxfordshire, England.

Supporting an international community

Isis supports an international community of more than 2,000 scientists who use neutrons and muons for research in physics, chemistry, materials science, geology, engineering and biology. It is the most productive research centre of its type in the world.

Neutron scattering is a vital research and analysis technique in exploring the structure and dynamics of materials and molecules. It provides unique and complementary information to that available from synchrotron light sources.

The Isis second target station project complements the facilities already operating at Isis and enables the science programme to expand into the key research areas of soft matter, advanced materials and bioscience. The experimental programme at the new target station will begin in October 2008.