Bone: ultrastructure, mineralogy and chemistry

骨骼是构成我们骨骼的材料，是一种精细的工程材料，由矿物质和胶原蛋白两种成分等量组成。这种矿物质由钙和磷酸盐的微小晶体组成，这是我们身体中必不可少的两种化学物质。胶原蛋白是一种蛋白质，是我们体内含量最多的一种蛋白质，也存在于皮肤和肌腱中。骨骼的胶原蛋白形成了一缕一缕的“原纤维”，它们捆绑在一起，沿着我们长骨的轴线排列，但是矿物质在哪里呢？以前的研究人员认为它主要存在于胶原蛋白内部，填补了端到端胶原蛋白分子之间的小空隙。然而，我们的研究表明，这种观点是错误的，骨骼中几乎所有的矿物质都以细长支柱的形式存在，这些支柱与胶原原纤维平行，并像木棒围绕木桶一样堆积在它们周围。这些支柱本身是由更小的晶体片组成的，它们显然是粘在一起形成支柱的。我的研究目标是提高我们对这个新发现的结构的理解，并学习它是如何形成的。我将利用强大的电子显微镜，让我们看到构成骨头的最小结构。使用化学试剂，我们将骨骼拆开，提取整个矿物支柱，这样我们就可以研究它们的形式以及它们如何有助于骨骼的强度。我还将与麦克马斯特大学的生物医学工程师合作，他们正在通过在显微镜下研究活骨与金属接触的情况，来确定如何制造出最好的金属植入物。虽然大多数陆地动物的骨头在亚微观尺度下看起来很相似，但鱼类的骨头看起来却奇怪地不同。我将在电子显微镜下研究鱼骨，并试图了解陆地动物是如何从鱼类进化而来的，如何发展出一种不同的骨头，这种骨头更适合于支持它们抵抗重力。***这项研究有助于我们了解人类和动物的骨骼是如何形成的，它可以引导医学科学家开发治疗骨骼疾病的新疗法。我们的研究也将有助于改善骨植入和骨折愈合的结果。这些都是许多加拿大人关注的主要健康问题。* * * * * * * *

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. ********