دانلود رایگان مقاله میکرو ناهمگنی مکانیکی کورتیکال استخوان حاکم بر فعالیت استئوکلاست

Abstract

Human cortical bone permanently remodels itself resulting in a haversian microstructure with heterogeneous mechanical and mineral properties. Remodeling is carried out by a subtle equilibrium between bone formation by osteoblasts and bone degradation by osteoclasts. The mechanisms regulating osteoclast activity were studied using easy access supports whose homogeneous microstructures differ from human bone microstructure. In the current study, we show that human osteoclasts resorb human cortical bone non-randomly with respect to this specific human bone microstructural heterogeneity. The characterization of this new resorption profile demonstrates that osteoclasts preferentially resorb particular osteons that have weak mechanical properties and mineral contents and that contain small hydroxyapatite crystals with a high carbonate content. Therefore, the influence of human bone microstructure heterogeneity on osteoclast activity could be a key parameter for osteoclast behaviour, for both in vitro and clinical studies.

4. Discussion

The goal of our study was to better understand the links between the mechanical properties of the human cortical bone surface and human osteoclast mediated resorption. To date, the vast majority of in vitro studies on osteoclast mediated bone degradation have been performed using cortical bovine bone, dentin or biomaterials, which provide relatively homogeneous surfaces [27–29]. In contrast, the human haversian cortical bone microstructure is composed of osteonal units [30] derived from the remodeling process, implying osteoclast activity. The elastic modulus and mineral content were shown to be almost constant inside the same osteon, but variable across osteons [16, 31 and 32]. The hardest tissues inside the microstructure are interstitial tissues that are mainly composed of the remains of aging osteons [33].