We use our skeleton every day, but our mental model of our bones may look more like a glow-in-the-dark Halloween costume, or a teaching skeleton hanging on a sitcom set, than true anatomy. While these common representations of skeletons focus on the sturdy aspects of bones, the structural frames of actual bones are built by a soft organic portion. To create bones, the human body precipitates calcium phosphate minerals using collagen, a long protein, as scaffolding. Our bodies mineralize calcium phosphate both inside and outside collagen-confined spaces, and scientists are still working to understand how the two types of mineralization occur. Recent research at the U.S. Department of Energy’s Advanced Photon Source (APS) has investigated mineralization rates and shown that collagen structures reduce the energy barriers to mineralization by providing a substrate on which the calcium phosphate can precipitate. Since common bone diseases, such as osteoporosis, hinge on an abnormal calcium phosphate precipitation process, this improved understanding of the role of collagen in precipitation could lead to insight into the treatment of these diseases.
Figure (extract, full image here) This scanning electron microscopy image shows calcium phosphate minerals nucleation in both extrafibrillar (purple colored image) and intrafibrillar (green colored image) spaces of collagen matrices. Without polyaspartic acid, extrafibrillar nucleation of calcium phosphate is dominant while with polyaspartic acid, intrafibrillar nucleation mainly occurs.