Silicate performs strongly at bone regeneration

Biomaterials scientists in Taiwan have developed a quick-setting cement that could help broken bones to regenerate.

A biocompatible layer of bone-like apatite nodules forms on the cement's surface when it is immersed in a physiological solution

Calcium phosphates were developed over 20 years ago as alternatives to polymer-based cements for mending damaged bones. Their chemical similarity to bone means that they are good repair materials and they are less toxic and more fracture-resistant than polymer cements. However, the absence of silicon - thought to be an important trace element in the early stages of bone formation - means that calcium phosphate cements are not perfect when it comes to integrating with living tissue.

By using silicate rather than phosphate, a team led by Shinn-Jyh Ding at Chung-Shan Medical University, Taichung, has developed a quick-setting cement with promising biological properties. Earlier calcium silicate formulations had setting times of over an hour, which is too long for clinical applications, says Ding, but the new cement sets in just five minutes. It should be a good candidate for bone replacements, he adds, because a biocompatible layer of bone-like apatite nodules forms on the cement's surface when it is immersed in a physiological solution. Ding says that tests in vitro suggest that the cement should encourage the growth of osteoblasts, the cells that are responsible for generating bone tissue, opening up the possibility of its use as an implant material.

"This work broadens our knowledge in this growing field, and I look forward to reading further studies by this group"
- Jake Barralet, McGill University, Montreal, Canada

Future research by the group, says Ding, will focus on improving the injectability and durability of the cement, which he suggests might be achieved by adding natural materials such as gelatin and chitosan.

Jake Barralet, a specialist in bioceramics at McGill University, Montreal, Canada, says that materials that stimulate tissue repair are the 'next big thing' in regenerative medicine. 'It is not yet clear precisely what material parameters cause cell differentiation and tissue regeneration in bone, but this work broadens our knowledge in this growing field, and I look forward to reading further studies by this group,' he says.

David Barden

http://www.rsc.org/Publishing/ChemTech/Volume/2009/03/silicate_cement.asp