Bone: ultrastructure, mineralogy and chemistry

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Bone, the material out of which our bones are constructed, is a finely engineered material made of equal amounts of two components: mineral and collagen. The mineral consists of tiny crystals of a salt of calcium and phosphate, two of the essential chemicals in our body. Collagen is a protein, the most abundant one in our body, also found in skin and tendons. The collagen of bone forms wispy “fibrils” that are bundled together and lined up along the axes of our long bones, but where is the mineral? Previous researchers thought that it was mainly inside the collagen, filling little gaps between end-to-end molecules of collagen. Our research has shown, however, that this view is mistaken, and that almost all the mineral in bone is in the form of slender struts that run parallel to the collagen fibrils and are stacked around them like staves around a barrel. These struts are themselves composed of even smaller crystal flakes that are apparently glued together to make the struts. My research will be targeted on improving our understanding of this newly discovered structure, and learning how it is formed. I will make use of powerful electron microscopes that allow us to visualize the smallest structures that make up bone. Using chemical reagents, we will take apart bone and extract the mineral struts whole, so that we can study their form and how they contribute to the strength of bone. I will also collaborate with biomedical engineers at McMaster who are determining how to create the best metal implants to be inserted into bones, by studying under the microscope what happens where the living bone meets metal. Even though most bone from land animals looks quite similar when viewed at this submicroscopic scale, bone from fish looks oddly different. I will study fish bone under the electron microscope and try to learn how land animals, evolved from fish, developed a different kind of bone that was better suited to supporting them against the force of gravity. By contributing to our knowledge of how bone is constructed in humans and animals, this research can lead to the development by medical scientists of new therapies for diseases of bone. Our studies will also aid in improving the outcome of bone implants and fracture healing. These represent major health concerns for many Canadians.